CHALK, David L.
Bournemouth Trolleybuses - Official Souvenir Brochure 1933 - 1969: 36 Years of Service
CHALLIS, W.H.
Principles of the Layout of Signals (British Practice)
The Institution of Railway Signal Engineers Booklet No. 1
CHALLIS, W.H.
Holding the Route
The Institution of Railway Signal Engineers Booklet No. 16
CHALLIS, W.H.
Track Circuits (British Practice)
The Institution of Railway Signal Engineers Booklet No. 9
