1. Capelle..Bl., 1862 (4),3, 151 (cited fromBeilstein, 1934,Bd. 19, 18).
2. Challenger and Harrison..J. Inst. Petroleum Techn., 1935,21, 135.
3. Cox, Gillot and Jaffery..Acta Cryst., 1949,2, 356. Longett-Higgins ..Ibid., 1950,3, 76.
4. Challenger and Gibson ..J.C.S., 1940, 305.
5. -, Fishwick and HolmesChem. and Ind., 1952, 519.