There is plenty of resources out there for further research into the Rotherham Trolleybus System, public transport in general or Rotherham itself. Unfortunatly many of the books are out of print, but local libraries do keep copies of the following resources we recommend:
Rotherham Transport History: A Photographic Journey ISBN: 0860670910
Rotherham and District Transport Vol 1 to 1914 ISBN: 0903666898
Rotherham and District Transport Vol 2 to 1939 ISBN: 0903666928
Rotherham and District Transport Vol 3 1939 to 1974 ISBN: 0903666936
Mexborough and Swinton Trolleybuses ISBN: 1906008361

Resources available to buy

There are a few titles still available to buy, below are links to some that we have found:

Rotherham Trolleybuses 
Remember The Trackless: Mexborough Swinton Rotherham - DVD - Online Video 
Rotherham Past and Present: The Changing Face of the Area and Its People 
Mexborough and Swinton Trolleybuses 
History of the Mexborough and Swinton Traction Company 
British Buses, Trams and Trolleybuses 1950s-1970s: South, West and North Yorkshire v. 5 (Road Transport Heritage)