J C Gillham, The Waterloo & City Railway, Oakwood Press, Usk, 2001, ISBN 0-85361-525-X
Nigel Pennick, Waterloo and City Railway, Library of the European Tradition, Cambridge, 2000
The Engineer periodical dated 26 July 1895 and 2 August 1895 gives much more detail of the construction of the tunnels, the Greathead shield, the compressed air working and the electric locomotives, including a diagram of them. On-line versions of the periodical are available at Graces Guide [2].
Proceedings of the Institution of Civil Engineers, Volume CXXXIX, 1899 - 1900 gives an extensive description of the construction phase