APA (6th ed.):
ProCon.org. (2013, June 27). Historical Timeline: History of Alternative Energy and Fossil Fuels. Retrieved from https://www.procon.org/historical-timeline-history-of-alternative-energy-and-fossil-fuels/
[Editor's Note: The APA citation style requires double spacing within entries.]
Chicago (17th ed.):
ProCon.org, "Historical Timeline: History of Alternative Energy and Fossil Fuels," ProCon.org. last modified June 27, 2013. https://www.procon.org/historical-timeline-history-of-alternative-energy-and-fossil-fuels/.
MLA (8th ed.):
ProCon.org, "Historical Timeline: History of Alternative Energy and Fossil Fuels." ProCon.org. 27 June 2013, www.procon.org/historical-timeline-history-of-alternative-energy-and-fossil-fuels/
[Editor’s Note: The MLA citation style requires double spacing within entries.]
Turabian (8th ed.):
ProCon.org. "Historical Timeline: History of Alternative Energy and Fossil Fuels." ProCon.org. Last modified on June 27, 2013. Accessed January 16, 2021. https://www.procon.org/historical-timeline-history-of-alternative-energy-and-fossil-fuels/