1. J. H. van’t Hoff, Archiv Neerland Sci. Exact Nat., 9, 445 (1874)
2. A. Lebel, Bull. Soc. Chim., 22, 337 (1874)
3. L. F. Fieser and M. Fieser, ‘Organic Chemistry’, Reinhold Pub. Corp., NY (1956)
4. E. Fischer and J. Hirschberger, Ber., 22, 365 (1889)
5. G. Natta, M. Farina, and M. Peraldo, Makromol. Chem., 38, 13 (1960)