1. Steel, J.G. and Bradfield, R. (1934), Am. Soil Survey Assoc. Rep., 14th Ann. Mtg Bull., No. 15, 88.
2. Marshall, C.E. (1930), Proc. R. Soc., A126, 427.
3. Whitby, K.T. (1955), Heat, Pip. Air Condit., 61, 449.
4. Whitby, K.T. (1955), J. Air Poll. Control Ass., 5, 120.
5. Whitby, K.T., Algren, A.B. and Annis, J.C. (1958), ASTM Sp. Publ. No. 234, 117.