as a result of our investment philosophy , we can not assure you that our newer products and services , or any other products and services we may introduce or acquire , will be integrated effectively into our business , achieve or sustain profitability or achieve market acceptance at levels sufficient to justify our investment . our strategy for achieving and maintaining profitability is centered upon our ability to expand the number of students using our products and services and increase student engagement with our connected learning platform . for the foreseeable future we expect to continue to invest in our print textbook business as a means of expanding student acquisition and generating operating cash flow . to deepen student engagement we will continue to invest in the expansion of our non-print products and digital services to provide a more compelling and personalized solution . we believe this expanded and deeper penetration of the student demographic will allow us to drive growth in our enrollment and brand marketing services . in addition , we believe that the investments we have made to achieve our current scale will allow us to drive increased operating margins over time that , together with increased contributions of higher margin non-print products and digital services , will enable us to accomplish profitability and become cash-flow positive for the long-term . our ability to accomplish these long-term objectives is subject to numerous risks and uncertainties , including our ability to attract , retain and increasingly engage the student population , intense competition in our markets , the ability to achieve sufficient contributions from our non-print products and digital services and other factors described in greater detail in risk factors. our print textbook business we were founded in 2005 to help students reduce the cost of college and we launched our online print textbook rental business in 2007. we saw that outside of tuition , fees , room and board , print textbooks are one of the most burdensome costs of higher education , and we worked to develop a sustainable business model that could solve this problem for students . our core idea was to purchase textbooks , rent them to students for the academic term at a substantial discount from list price to attract volume and realize return on our investment by renting the same book over multiple academic terms . we began to achieve substantial scale in 2010 when net revenues more than tripled compared to the prior year . leveraging the business intelligence we gained from operating at scale , in 2011 , we reduced our rental catalog to include only those titles with sufficient demand to support our economic model , contributing to the reduced revenue growth rate during the year . at the same time , in order to continue to offer students a comprehensive textbook selection at a substantial savings compared to retail prices available from other vendors , we made print textbooks lacking sufficient demand to support the rental model available for purchase on our website at a slight mark-up to our cost . this had the effect of shifting textbooks with a lower acquisition cost or lower demand from our rental catalog to our sales catalog . we also increasingly use our website to liquidate textbooks from our textbook library , which allows us to generate greater recovery on our textbooks compared to bulk liquidations , while at the same time providing students substantial savings over the retail price of a new book . we are able to adjust what we liquidate based on expected rental demand . as an example , in the second half of 2013 , we elected to optimize our textbook library more for rental than liquidation in anticipation of greater rental demand for the winter rush cycle . this decision led to less site liquidations in that quarter of the 46 books that typically have higher source cost recovery but also increased our available inventory of books for rent . we source both new and used print textbooks for rental or resale from wholesalers , publishers and students . purchasing used textbooks allows us to reduce the investments necessary to maintain our textbook library while at the same time attracting students to our website by offering them more for their textbooks than they could generally get by selling them back to their campus bookstore . through these refinements to our model , we have achieved greater overall efficiency , enabling us to lower our per unit rental rates , which has driven revenue growth and , to a greater extent , print textbook unit volumes beginning in 2012. our print textbook rental business is highly capital intensive . while we generate positive cash flows from operations on an annual basis , this has been more than offset by the cash we use for our investing activities , primarily due to the purchase of print textbooks . we expect this trend to continue in the foreseeable future . we capitalize the investment in our textbook library and record depreciation expense in cost of revenues over its useful life using an estimated liquidation value . in 2013 , our investment in print textbooks , net of proceeds from textbook liquidation , was $ 84.3 million . our non-print products and digital services business building on the rapid adoption and high engagement of students with our print textbook offerings , in 2010 we set out to offer digital content and solutions and create our student-first connected learning platform to address other critical aspects of the education process . with the advent of etextbooks , we developed a web-based , multiplatform etextbook reader and offer etextbooks and supplemental materials from approximately 120 publishers both as a rental-equivalent solution and for free for students awaiting the arrival of their print textbook rental . in the fourth quarter of 2010 , we purchased cramster , a company that provided online homework help for college students . story_separator_special_tag we anticipate that our non-print products and digital services will continue to grow at a rate greater than our overall revenue growth in future periods . net revenues in 2012 increased $ 41.3 million , or 24 % , compared to 2011. the increase in net revenues was due primarily to an increase in print textbook volumes of 22 % , resulting from an increase in rental units . non-print products and digital services represented 7 % of net revenues during 2011 and 13 % of net revenues during 2012 , increasing by 142 % in absolute dollars during 2012 due to a full year of enrollment marketing services as a result of our acquisition of zinch in october 2011 and growth in new memberships for our chegg study service . 52 cost of revenues the following table sets forth our cost of revenues for the periods shown ( dollars in thousands ) : replace_table_token_6_th cost of revenues in 2013 increased $ 29.4 million , or 20 % , compared to 2012. the increase was primarily due to an increase in order fulfillment and payment processing costs of $ 10.3 million , textbook depreciation of $ 7.6 million and cost of digital content of $ 2.5 million . the increase in order fulfillment costs , in particular etextbook fees and payment processing fees , is directly attributable to the increase in textbook unit volumes during 2013. textbook depreciation increased primarily due to our purchases of textbooks during the year . the cost of digital content increased during the year due to our expansion of digital content solutions made available to students . in addition , we experienced an increase in the cost of textbooks purchased on a just-in-time basis of approximately $ 5.3 million , which was primarily driven by an increase in the number of units sold . we also experienced increased costs of approximately $ 2.7 million associated with hiring temporary personnel to assist with higher transaction and textbook volumes during 2013 and higher write-offs of $ 1.3 million . cost of revenues as a percentage of net revenues was flat from 2013 to 2012. cost of revenues in 2012 increased $ 18.7 million , or 15 % , compared to 2011. the increase was primarily due to an increase in order fulfillment costs of $ 13.7 million , cost of digital content of $ 3.8 million and textbook depreciation of $ 1.0 million . the increase in order fulfillment costs is directly attributable to the increase in textbook unit volumes in 2012 compared to 2011. the cost of digital content increased in 2012 due to our expansion of digital content solutions we developed or licensed from publishers and made available to students . textbook depreciation increased primarily due to the expansion of our textbook library . cost of revenues as a percentage of net revenues decreased to 68 % for 2012 from 74 % for 2011 , primarily due to the increase in our net revenues from higher margin non-print products and digital services . operating expenses the following table sets forth our operating expenses for the periods shown ( dollars in thousands ) : replace_table_token_7_th 53 technology and development technology and development expenses during 2013 increased $ 2.6 million , or 7 % , compared to 2012. during 2013 our employee-related expenses increased $ 3.2 million compared to the prior year . in addition , stock-based compensation expense increased by $ 1.8 million primarily due to the grant of vested rsus and the vesting of previously outstanding rsus to officers and consultants , which resulted in additional stock-based compensation expense upon the completion of our ipo . these increases were partially offset by a decrease in amortization of intangible assets as intangibles acquired during 2011 became fully amortized . in addition , as we hired full-time employees we reduced our usage of contractors , resulting in savings of approximately $ 0.6 million during 2013 compared to 2012. technology and development as a percentage of net revenues decreased to 16 % of net revenues in 2013 compared to 18 % of net revenues in 2012. technology and development expenses in 2012 increased $ 9.7 million , or 33 % , compared to 2011. technology and development as a percentage of net revenues increased to 18 % of net revenues in 2012 compared to 17 % of net revenues in 2011. the increase in absolute dollars and as a percentage of net revenues was due to an increase in employee related compensation and benefits of approximately $ 5.5 million , primarily driven by increased headcount during 2012. this increase was partially offset by a decrease in outside services of $ 1.6 million as a result of hiring full-time employees . we also experienced an increase in stock-based compensation expense during 2012 of approximately $ 3.8 million . this increase is primarily the result of the full year impact of stock-based compensation expense as a result of the issuance of stock options and restricted shares of our common stock granted in conjunction with our acquisitions during prior years , as well as an increase in new grants . amortization of intangible assets increased $ 2.2 million due to a full year of amortization for technology acquired during 2011 through our acquisitions . sales and marketing sales and marketing expenses during 2013 decreased by $ 0.8 million , or 2 % , compared to 2012. sales and marketing expenses as a percentage of net revenues decreased to 20 % during 2013 compared to 24 % of net revenues during 2012. the decrease in absolute dollars and as a percentage of net revenues is primarily attributable to a decrease in advertising and marketing expenses of $ 5.1 million as a result of improved performance of search engine optimization and increased direct traffic resulting in decreased reliance on paid advertising , which were outperforming paid search advertising primarily utilized during 2012. there was a decrease of $ 0.9 million in amortization of

cash flows from operating activities although we incurred net losses in 2013 , 2012 and 2011 , we generated positive cash flows from operating activities in each period presented , which was primarily the result of our increased textbook revenue . cash flows from operating activities are also influenced by the increase in expenses we incur to support the growth in our business . the substantial majority of our net revenue is from e-commerce transactions with students , which are settled immediately through payment processors , and our accounts payable are settled based on contractual payment terms with our suppliers . as a result , changes in our operating accounts are generally a source of cash overall , although they can be a use of cash in the second and fourth quarters of each year as payables become due and new bookings are generally at their low point . in addition , we have significant non-cash operating expenses such as textbook library depreciation expense , other depreciation and amortization expense and stock-based compensation expense . in 2013 , 2012 and 2011 , our non-cash operating expenses and changes in operating assets and liabilities more than offset our net loss . net cash provided by operating activities in 2013 was $ 63.7 million . although we incurred a net loss of $ 55.9 million , our net loss was more than offset by significant non-cash operating expenses , including textbook library depreciation expense of $ 64.8 million , other depreciation and amortization expense of $ 11.6 million , stock-based compensation expense of $ 37.0 million and loss from write-offs of textbooks of $ 5.9 million . net cash provided by operating activities in 2012 was $ 54.7 million . although we incurred a net loss of $ 49.0 million , our net loss was offset by significant non-cash operating expenses , including textbook library depreciation expense of $ 57.2 million , other depreciation and amortization expense of $ 12.6 million , stock-based compensation expense of $ 18.0 million and loss from write-offs of textbooks of $ 4.6 million . net cash provided by operating activities in 2011 was $ 32.8


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```cash flows from operating activities although we incurred net losses in 2013 , 2012 and 2011 , we generated positive cash flows from operating activities in each period presented , which was primarily the result of our increased textbook revenue . cash flows from operating activities are also influenced by the increase in expenses we incur to support the growth in our business . the substantial majority of our net revenue is from e-commerce transactions with students , which are settled immediately through payment processors , and our accounts payable are settled based on contractual payment terms with our suppliers . as a result , changes in our operating accounts are generally a source of cash overall , although they can be a use of cash in the second and fourth quarters of each year as payables become due and new bookings are generally at their low point . in addition , we have significant non-cash operating expenses such as textbook library depreciation expense , other depreciation and amortization expense and stock-based compensation expense . in 2013 , 2012 and 2011 , our non-cash operating expenses and changes in operating assets and liabilities more than offset our net loss . net cash provided by operating activities in 2013 was $ 63.7 million . although we incurred a net loss of $ 55.9 million , our net loss was more than offset by significant non-cash operating expenses , including textbook library depreciation expense of $ 64.8 million , other depreciation and amortization expense of $ 11.6 million , stock-based compensation expense of $ 37.0 million and loss from write-offs of textbooks of $ 5.9 million . net cash provided by operating activities in 2012 was $ 54.7 million . although we incurred a net loss of $ 49.0 million , our net loss was offset by significant non-cash operating expenses , including textbook library depreciation expense of $ 57.2 million , other depreciation and amortization expense of $ 12.6 million , stock-based compensation expense of $ 18.0 million and loss from write-offs of textbooks of $ 4.6 million . net cash provided by operating activities in 2011 was $ 32.8
```    
 Suspicious Activity Report : as a result of our investment philosophy , we can not assure you that our newer products and services , or any other products and services we may introduce or acquire , will be integrated effectively into our business , achieve or sustain profitability or achieve market acceptance at levels sufficient to justify our investment . our strategy for achieving and maintaining profitability is centered upon our ability to expand the number of students using our products and services and increase student engagement with our connected learning platform . for the foreseeable future we expect to continue to invest in our print textbook business as a means of expanding student acquisition and generating operating cash flow . to deepen student engagement we will continue to invest in the expansion of our non-print products and digital services to provide a more compelling and personalized solution . we believe this expanded and deeper penetration of the student demographic will allow us to drive growth in our enrollment and brand marketing services . in addition , we believe that the investments we have made to achieve our current scale will allow us to drive increased operating margins over time that , together with increased contributions of higher margin non-print products and digital services , will enable us to accomplish profitability and become cash-flow positive for the long-term . our ability to accomplish these long-term objectives is subject to numerous risks and uncertainties , including our ability to attract , retain and increasingly engage the student population , intense competition in our markets , the ability to achieve sufficient contributions from our non-print products and digital services and other factors described in greater detail in risk factors. our print textbook business we were founded in 2005 to help students reduce the cost of college and we launched our online print textbook rental business in 2007. we saw that outside of tuition , fees , room and board , print textbooks are one of the most burdensome costs of higher education , and we worked to develop a sustainable business model that could solve this problem for students . our core idea was to purchase textbooks , rent them to students for the academic term at a substantial discount from list price to attract volume and realize return on our investment by renting the same book over multiple academic terms . we began to achieve substantial scale in 2010 when net revenues more than tripled compared to the prior year . leveraging the business intelligence we gained from operating at scale , in 2011 , we reduced our rental catalog to include only those titles with sufficient demand to support our economic model , contributing to the reduced revenue growth rate during the year . at the same time , in order to continue to offer students a comprehensive textbook selection at a substantial savings compared to retail prices available from other vendors , we made print textbooks lacking sufficient demand to support the rental model available for purchase on our website at a slight mark-up to our cost . this had the effect of shifting textbooks with a lower acquisition cost or lower demand from our rental catalog to our sales catalog . we also increasingly use our website to liquidate textbooks from our textbook library , which allows us to generate greater recovery on our textbooks compared to bulk liquidations , while at the same time providing students substantial savings over the retail price of a new book . we are able to adjust what we liquidate based on expected rental demand . as an example , in the second half of 2013 , we elected to optimize our textbook library more for rental than liquidation in anticipation of greater rental demand for the winter rush cycle . this decision led to less site liquidations in that quarter of the 46 books that typically have higher source cost recovery but also increased our available inventory of books for rent . we source both new and used print textbooks for rental or resale from wholesalers , publishers and students . purchasing used textbooks allows us to reduce the investments necessary to maintain our textbook library while at the same time attracting students to our website by offering them more for their textbooks than they could generally get by selling them back to their campus bookstore . through these refinements to our model , we have achieved greater overall efficiency , enabling us to lower our per unit rental rates , which has driven revenue growth and , to a greater extent , print textbook unit volumes beginning in 2012. our print textbook rental business is highly capital intensive . while we generate positive cash flows from operations on an annual basis , this has been more than offset by the cash we use for our investing activities , primarily due to the purchase of print textbooks . we expect this trend to continue in the foreseeable future . we capitalize the investment in our textbook library and record depreciation expense in cost of revenues over its useful life using an estimated liquidation value . in 2013 , our investment in print textbooks , net of proceeds from textbook liquidation , was $ 84.3 million . our non-print products and digital services business building on the rapid adoption and high engagement of students with our print textbook offerings , in 2010 we set out to offer digital content and solutions and create our student-first connected learning platform to address other critical aspects of the education process . with the advent of etextbooks , we developed a web-based , multiplatform etextbook reader and offer etextbooks and supplemental materials from approximately 120 publishers both as a rental-equivalent solution and for free for students awaiting the arrival of their print textbook rental . in the fourth quarter of 2010 , we purchased cramster , a company that provided online homework help for college students . story_separator_special_tag we anticipate that our non-print products and digital services will continue to grow at a rate greater than our overall revenue growth in future periods . net revenues in 2012 increased $ 41.3 million , or 24 % , compared to 2011. the increase in net revenues was due primarily to an increase in print textbook volumes of 22 % , resulting from an increase in rental units . non-print products and digital services represented 7 % of net revenues during 2011 and 13 % of net revenues during 2012 , increasing by 142 % in absolute dollars during 2012 due to a full year of enrollment marketing services as a result of our acquisition of zinch in october 2011 and growth in new memberships for our chegg study service . 52 cost of revenues the following table sets forth our cost of revenues for the periods shown ( dollars in thousands ) : replace_table_token_6_th cost of revenues in 2013 increased $ 29.4 million , or 20 % , compared to 2012. the increase was primarily due to an increase in order fulfillment and payment processing costs of $ 10.3 million , textbook depreciation of $ 7.6 million and cost of digital content of $ 2.5 million . the increase in order fulfillment costs , in particular etextbook fees and payment processing fees , is directly attributable to the increase in textbook unit volumes during 2013. textbook depreciation increased primarily due to our purchases of textbooks during the year . the cost of digital content increased during the year due to our expansion of digital content solutions made available to students . in addition , we experienced an increase in the cost of textbooks purchased on a just-in-time basis of approximately $ 5.3 million , which was primarily driven by an increase in the number of units sold . we also experienced increased costs of approximately $ 2.7 million associated with hiring temporary personnel to assist with higher transaction and textbook volumes during 2013 and higher write-offs of $ 1.3 million . cost of revenues as a percentage of net revenues was flat from 2013 to 2012. cost of revenues in 2012 increased $ 18.7 million , or 15 % , compared to 2011. the increase was primarily due to an increase in order fulfillment costs of $ 13.7 million , cost of digital content of $ 3.8 million and textbook depreciation of $ 1.0 million . the increase in order fulfillment costs is directly attributable to the increase in textbook unit volumes in 2012 compared to 2011. the cost of digital content increased in 2012 due to our expansion of digital content solutions we developed or licensed from publishers and made available to students . textbook depreciation increased primarily due to the expansion of our textbook library . cost of revenues as a percentage of net revenues decreased to 68 % for 2012 from 74 % for 2011 , primarily due to the increase in our net revenues from higher margin non-print products and digital services . operating expenses the following table sets forth our operating expenses for the periods shown ( dollars in thousands ) : replace_table_token_7_th 53 technology and development technology and development expenses during 2013 increased $ 2.6 million , or 7 % , compared to 2012. during 2013 our employee-related expenses increased $ 3.2 million compared to the prior year . in addition , stock-based compensation expense increased by $ 1.8 million primarily due to the grant of vested rsus and the vesting of previously outstanding rsus to officers and consultants , which resulted in additional stock-based compensation expense upon the completion of our ipo . these increases were partially offset by a decrease in amortization of intangible assets as intangibles acquired during 2011 became fully amortized . in addition , as we hired full-time employees we reduced our usage of contractors , resulting in savings of approximately $ 0.6 million during 2013 compared to 2012. technology and development as a percentage of net revenues decreased to 16 % of net revenues in 2013 compared to 18 % of net revenues in 2012. technology and development expenses in 2012 increased $ 9.7 million , or 33 % , compared to 2011. technology and development as a percentage of net revenues increased to 18 % of net revenues in 2012 compared to 17 % of net revenues in 2011. the increase in absolute dollars and as a percentage of net revenues was due to an increase in employee related compensation and benefits of approximately $ 5.5 million , primarily driven by increased headcount during 2012. this increase was partially offset by a decrease in outside services of $ 1.6 million as a result of hiring full-time employees . we also experienced an increase in stock-based compensation expense during 2012 of approximately $ 3.8 million . this increase is primarily the result of the full year impact of stock-based compensation expense as a result of the issuance of stock options and restricted shares of our common stock granted in conjunction with our acquisitions during prior years , as well as an increase in new grants . amortization of intangible assets increased $ 2.2 million due to a full year of amortization for technology acquired during 2011 through our acquisitions . sales and marketing sales and marketing expenses during 2013 decreased by $ 0.8 million , or 2 % , compared to 2012. sales and marketing expenses as a percentage of net revenues decreased to 20 % during 2013 compared to 24 % of net revenues during 2012. the decrease in absolute dollars and as a percentage of net revenues is primarily attributable to a decrease in advertising and marketing expenses of $ 5.1 million as a result of improved performance of search engine optimization and increased direct traffic resulting in decreased reliance on paid advertising , which were outperforming paid search advertising primarily utilized during 2012. there was a decrease of $ 0.9 million in amortization of

