<https://gearvn.com/blogs/thu-thuat-giai-dap/skype-la-gi-cach-tai-skype-ve-may-tinh-dien-thoai-thanh-cong>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://gearvn.com/blogs/thu-thuat-giai-dap/skype-la-gi-cach-tai-skype-ve-may-tinh-dien-thoai-thanh-cong>