1. Bruckner, V., Ber., 75, 2034 (1942).
2. Hudson, B. J. F., and Robinson, R., J. Chem. Soc., 715 (1941).
3. Tamayo, M. L., and Ayestarán, D., An. Fisica Quim., 36, 44 (1940); 37, 392 (1941). These authors did not recognize that the uncrystallizable compound (m.p. 311–312°, decomp.) prepared by them was a heteropolymer.
4. Alder, K., Angew. Chem., 50, 510 (1937).
5. Wagner-Jauregg, Th., Ber., 63, 3218 (1930); Ann., 491, 1 (1931).