American Institute of Certified Public Accountants. Returning to Work After You've Retired. http://www.360financialliteracy.org/Topics/Retirement-Planning/Retirement-Planning-Basics/Returning-to-Work-After-You-ve-Retired. Accessed May 6, 2016.
Social Security Administration. How Work Affects Your Benefits. https://www.ssa.gov/pubs/EN-05-10069.pdf. 2016. Accessed May 6, 2016.