McCord, Mr. Kent R. “The Past, Present, and Future of Phosphoric Acid Fuel Cells Operating on Anaerobic Digester Gas”. Distributed Generation & Alternative Energy Journal 22, no. 4 (October 17, 2007): 57–71. Accessed May 14, 2026. https://journals.riverpublishers.com/index.php/DGAEJ/article/view/14235.