1. J. E. Gillott, Canad. Mineralogist 10 (1971) 797.
2. I. J. Smalley, Nature 231 (1971) 310.
3. R. A. Sevaldson, Norwegian Geotech. Inst. Publ. 24 (1957) 1.
4. F. Tavenas, J-Y. Chagnon, and P. La. Rochelle, Canad. Geotechnical J. 8 (1971) 464.
5. E. Penner, Nature 197 (1963) 347.