Nizamov, Il'Yas S.; Al'Metkina, Lyubov' A.; Garifzyanova, Gyuzel' G.; Batyeva, Elvira S.; Al'Fonsov, Vladimir A.; Pudovik, Arkady N. Phosphorus, Sulfur and Silicon and the Related Elements, 1993 , vol. 83, # 1-4 p. 191 - 202