APA (6th ed.):
ProCon.org. (2013, August 8). Historical Timeline. Retrieved from https://www.procon.org/historical-timeline-4/
[Editor's Note: The APA citation style requires double spacing within entries.]
Chicago (17th ed.):
ProCon.org, "Historical Timeline," ProCon.org. last modified August 8, 2013. https://www.procon.org/historical-timeline-4/.
MLA (8th ed.):
ProCon.org, "Historical Timeline." ProCon.org. 8 Aug. 2013, www.procon.org/historical-timeline-4/
[Editor’s Note: The MLA citation style requires double spacing within entries.]
Turabian (8th ed.):
ProCon.org. "Historical Timeline." ProCon.org. Last modified on August 8, 2013. Accessed April 13, 2021. https://www.procon.org/historical-timeline-4/