1. Ackermann, W.: Collegium 1932, 828
2. Ackermann, W.: Chem. Zentralblatt 1933
I, 719.
3. Banerjee, Pares Chandra: Journ. Indian Chem. Ser. 12, 198 (1935)
4. Banerjee, Pares Chandra: Chem. Zentralblatt 1936 II, 1392.
5. Berthet, M.: Moniteur Produits Chim. 18, 3 (1936)