Angelov, Christo M.; Enchev, Dobromir D.
Phosphorus and Sulfur and the Related Elements, 1988 , vol. 37, p. 125 - 128

Bock, Hans; Aygen, Sitki; Rosmus, Pavel; Solouki, Bahman; Weissflog, Eckhard
Chemische Berichte, 1984 , vol. 117, # 1 p. 187 - 202