Nohab Foundation. Brief history of the class showing it's origins in the US General Motors EMD series of locos.
http://www.nohab-gm.com/en/en05_1.html
Nohab-GM M61 website showing every Hungarian loco and their eventual fates.
http://www.nohab.hu/indexeng.html http://www.nohab.hu/state.html