Bradford C. Snell 1974: American Ground Transport: A Proposal for Restructuring the Automobile, Truck, Bus and Rail Industries. Report presented to the Committee of the Judiciary, Subcommittee on Antitrust and Monopoly, United States Senate, February 26, 1974, United States Government Printing Office, Washington, 1974, pp. 16-24. Jürgen Burmeister 2009: Commuter Railways in den USA. Stadtverkehr 11/09, s. 46-47. Michael C.Duffy 2004: Electric railways 1880-1990. Saunders, D. WS Atkins Rail Ltd; ISSN: 0953-5683; http://books.google.no/books?id=cpFEm3aqz_MC&pg=PA147&lpg=PA147&dq=%22pcc+interurban%22&source=bl&ots=atmDLCpL2d&sig=5oefiLF3-3P1oQSISARCznHPfj8&hl=no&ei=0xmyS6GeIY-F-QbG2NmrAg&sa=X&oi=book_result&ct=result&resnum=2&ved=0CAoQ6AEwAQ#v=onepage&q=%22pcc%20interurban%22&f=true William D. Middleton: The interurban era, Kalmbach Publishing Co, 4. opplag 1968; http://www.archive.org/stream/interurbanera00midd/interurbanera00midd_djvu.txt.