1. Higman, Nature, 156, 242 (1945).
2. LeFevre, J. Soc. Chem. Ind., 49, 391 (1945).
3. Dewar, Nature, 156, 688 (1945).
4. For summary and references, see Brynmor Jones, Chem. Rev., 35, 335 (1945).
5. Brodsky and Micluchin., C.R. Acad. Sci. U.S.S.R., 32, 558 (1941). J. Chem. Phys., 11, 342 (1943).