2 April 2009. Retrieved 1 February 2011. ↑ "The 5 Whys and 5 Hows – When Clarity Is Just Two Questions Away". Retrieved 13 February 2017. ↑ http://northdenvernews.com/what-are-realistic-ways-to-become-rich/ ↑ Liker, Jeffrey; Meier, David (2006).