1. Wood, J. W. and Clayton, E. W., 48th Report of the Joint Research Committee of the Gas Research Board and the University of Leeds, copyright publication GRB 17, The Gas Research Board (presently the Gas Council) London (1945) (C.A. 42, 4327 f).
2. Bhatia, S. P., Ph.D. Thesis University of Aston in Birmingham (1967).