The following sources have been used in the preparation of "Railways of the Forest of Dean".
"Severn & Wye Railway : Volumes 1-3" by Ian Pope, Bob How and Paul Karau.
"Severn & Wye Railway : Volume 4" by Ian Pope and Paul Karau.
"The Forest of Dean Branch : Volumes 1-2" by Ian Pope and Paul Karau.
"Severn & Wye 180" published by the Dean Forest Railway Co. Ltd
"BR Steam in Dean : The photographs of Ben Ashworth" edited by Ian Pope
"Past & Present Vol 16 : Avon, Cotswolds and the Malverns" by Geoff Dowling and John Whitehouse. The book also features a substantial section on the railways of the Forest of Dean.
"Past & Present Vol 59 : Central Gloucestershire" by John Stretton.
"Past and Present Companions - Dean Forest Railway & ex-Severn & Wye Railway Lines, Volumes 1 & 2" by John Stretton
"Discovering Preserved Railways" by F G Cockman
"The Wye Valley Railway and the Coleford Branch" by B.M. Handley & R. Dingwall
"Hereford & Worcester Railways Remembered"/"Lost Railways of Hereford & Worcestershire" by Leslie Oppitz (The latter is an updated version of the former).
"The Ross, Monmouth and Pontypool Road Line", by Stanley C. Jenkins.
"Branch Lines around Ross-on-Wye" by Vic Mitchell and Keith Smith
"Branch Line to Monmouth" by Vic Mitchell and Keith Smith
"Branch Lines around Lydney" by Vic Mitchell and Keith Smith
"The Historical Survey of the Forest of Dean Railways : Layouts and Illustrations" by Peter Smith
"Rails to the Forest" by the Dean Forest Railway Museum Trust
"Rails through the Forest" by the Dean Forest Railway Museum Trust
"British Railway History in Colour Volume 1 : West Gloucester and Wye Valley Lines" by Neil Parkhouse
"British Railway History in Colour Volume 2 : Forest of Dean and the Severn Bridge" by Neil Parkhouse
"The Railway Magazine, August 2016 : Two Decades of Perrygrove" by Cliff Thomas
"Wye Valley Railway Story, Vol 1. 1855-1995" by Eric T Rawlings
I would recommend these books for anyone wishing to find out more about the history of the railways of the area and the collieries and other industries served by them.
Video/DVDs containing footage of the lines
B & R Video Productions Volume 99 : "Herefordshire Byways
B & R Video Productions Volume 120 : "South Wales Archive"
Bearleft.TV "Lost Railways of Forest of Dean : Severn & Wye"
Bearleft.TV "Lost Railways of Forest of Dean : Great Western Railway Forest of Dean Branch"