BR Regulations for Train Signalling on Double Lines by Track Circuit Block System, Supplement No.3 B.R. 29960/10, 20 pages.
Railway Book:BR-Regulations for Train Signalling and Signalmens General Duties
British Railways BR 29960 Regulations for Train Signalling 1st October 1960
EA07 - 011 - LNER - Regulations for Train Signaling on Single Lines - 1 Oct 1935
REGULATIONS FOR TRAIN SIGNALLING 1960 with SOUTHERN REGION SUPPLEMENT
British Railways Regulations for Train Examiners, Greasers and Oilers book 1947
SR Regulations for Train Signalling on Double and Singles Lines with amendment
