1. K. W. Earle, Dip and Strike Problems, London, 1934
2. B. C. Brown and F. Debenham, Structure and Surface, London, 1929
3. C. F. Tolman Jr., Graphical Solution of Fault Problems, San Francisco, 1911
4. M. H. Haddock, Disrupted Strata, London, 3rd edn, 1953.
5. Walcot Gibson, Coal in Great Britain, London, 1920, p. 81.