Sources
[1] Apple Inc. (AAPL) (2018). Yahoo Finance. Retrieved from: https://finance.yahoo.com/q?s=aapl&fr=uh3_finance_web&uhb=uhb2,
[2] GOOG (2018). Yahoo Finance. Retrieved from: http://finance.yahoo.com/q?s=XOM. Comparison date: April 30, 2018.
[3] Forbes Magazine (2016). “The Richest Person in Every State: Warren Buffett.” Retrieved from: http://www.forbes.com/profile/warren-buffett/