1. Arriienius, Sv.: Oetvers. Stockholm Akad. 6, 121 (1887).
2. Briggs, D. R.: Coll. Symp. Mon. 6, 41 (1928), NewYork.
3. Brintzinger, H.: Koll. Z. 43, 93 (1927).
4. Duclaux, J.: C. r. 140, 1468 (1925).
5. Duclaux, J.: Journ. Chim. Phys. 7, 405 (1909).