1. Simpson, A.: ‘Oscillations of catenaries and systems of overhead transmission lines’, 1963, Ph.D. Thesis, University of Bristol
2. Pestel, E.C., and Leckie, F.A.: Matrix methods in elasto-mechanics, (McGraw-Hill 1963)
3. Bishop, R.E.D., and Johnson, D.C.: The mechanics of vibration, (Cambridge University Press 1960)