Walden
Chemische Berichte, 1895 , vol. 28, p. 1295,1296
Zhurnal Russkago Fiziko-Khimicheskago Obshchestva, 1898 , vol. 30, p. 535,538

Kroehnke
Chemische Berichte, 1939 , vol. 72, p. 527,533