text: * Pacey, A. J. & Fisher, S. J. (1967) "Daniel Bernoulli and the vis viva of compressed air", The British Journal for the History of Science 3 (4), p. 388–392, 
  * British Transport Commission (1957) Handbook for Railway Steam Locomotive Enginemen, London : B.T.C.,  p. 81, (facsimile copy publ. Ian Allan (1977), )