APA (6th ed.):
ProCon.org. (2011, August 24). UPDATED: Timeline, 1990 – 2011. Retrieved from https://www.procon.org/updated-timeline-1990-2011/
[Editor's Note: The APA citation style requires double spacing within entries.]
Chicago (17th ed.):
ProCon.org, "UPDATED: Timeline, 1990 – 2011," ProCon.org. last modified August 24, 2011. https://www.procon.org/updated-timeline-1990-2011/.
MLA (8th ed.):
ProCon.org, "UPDATED: Timeline, 1990 – 2011." ProCon.org. 24 Aug. 2011, www.procon.org/updated-timeline-1990-2011/
[Editor’s Note: The MLA citation style requires double spacing within entries.]
Turabian (8th ed.):
ProCon.org. "UPDATED: Timeline, 1990 – 2011." ProCon.org. Last modified on August 24, 2011. Accessed January 15, 2021. https://www.procon.org/updated-timeline-1990-2011/