Reading list about electric railway/trolleybus traction
By no means comprehensive, but a start
UMTA report from May 1979: "The Status of Advanced Propulsion Systems for Urban Rail Vehicles"
UMTA report from October 1979: "The Trolley Coach: Development and State of the Art: Task 1 Report for the Electric Trolley Bus Feasibility Study"
"GVM - IK-280-as trolibuszok" page at villamosok.hu/troli (magyarul)
"GVM - IK-280 trolleybuses" hosted on said website (in English)
Ganz KCSV page on villamosok.hu (csak magyarul | only in Hungarian)
On the 50 kV electrification for Tumbler Ridge, courtesy Nixy Mouse