APA (6th ed.):
ProCon.org. (2009, May 13). Updated: Historical Timeline. Retrieved from https://www.procon.org/updated-historical-timeline-2/
[Editor's Note: The APA citation style requires double spacing within entries.]
Chicago (17th ed.):
ProCon.org, "Updated: Historical Timeline," ProCon.org. last modified May 13, 2009. https://www.procon.org/updated-historical-timeline-2/.
MLA (8th ed.):
ProCon.org, "Updated: Historical Timeline." ProCon.org. 13 May 2009, www.procon.org/updated-historical-timeline-2/
[Editor’s Note: The MLA citation style requires double spacing within entries.]
Turabian (8th ed.):
ProCon.org. "Updated: Historical Timeline." ProCon.org. Last modified on May 13, 2009. Accessed January 15, 2021. https://www.procon.org/updated-historical-timeline-2/