Golounin, A. V.; Shukhta, T. K.; Kirienko, E. K.; Petrova, M. P.; Esavkin, E. V.
Russian Journal of Applied Chemistry, 1994 , vol. 67, # 8.2 p. 1167 - 1169
Zhurnal Prikladnoi Khimii (Sankt-Peterburg, Russian Federation), 1994 , vol. 67, # 8 p. 1324 - 1327

Hugel et al.
Bulletin de la Societe Chimique de France, 1954 , p. 836,839