https://www.britannica.com/biography/Bill-Gates
https://money.cnn.com/2014/05/02/technology/gates-microsoft-stock-sale/
https://money.cnn.com/2014/03/03/news/companies/forbes-billionaire-rich-list/?iid=EL
https://www.forbes.com/profile/bill-gates/?list=billionaires#7e2e8d9c689f
http://www.freeinfosociety.com/article.php?id=74
https://www.thebalancesmb.com/public-company-vs-private-company-what-s-the-difference-398422
https://venturebeat.com/2020/01/29/microsoft-earnings-q2-2020/
https://www.wepc.com/news/video-game-statistics/
https://www.broadbandsearch.net/blog/online-gaming-statistics
https://web.archive.org/web/20070709062832/http://www.xbox.com/zh-SG/community/news/2006/20060510.htm
https://www.statista.com/statistics/680526/global-xbox-gaming-consoles-unit-sales/