USA Political Database Pictures:
- 111Alleskönner. "Political System of the United States". Wikipedia, 25 Nov 2012, https://en.wikipedia.org/wiki/Federal_government_of_the_United_States#/media/File:Political_System_of_the_United_States.svg
- Jackson, Bill. "Checks & Balances". The Social Studies Help Center, http://www.socialstudieshelp.com/lesson_13_notes.htm
- Sylvest, Pernille. "Modern Political Party Comparisons". Wikipedia, https://www.pinterest.com/pin/472666923384181540/?lp=true
- Wood, Gary. "Federalism Chart". An Eagle's Prayer, 26 Oct 2016, http://aneaglesprayer.org/american-federalism-history