1. Yamada, K.; Kinoshita, M.; Hosokawa, K.; Okuda, T.: Bull Chem Soc Jpn 66(1993),1317
2. Kravchenko, E.A.; Novoderezhkina, T.L.; Gilyarov, O.N.; Kulikovskii, B.N.; Lebedev, V.G.: Zh Neorg Khim 25(1980),1720
3. Sharma, V.K.; Richarz, W.; Sharma, S.; Weiss, A.: Z Naturforsch 45a(1990),545
4. Ishikawa, A.; Asaji, T.; Nakamura, D.; Ikeda, R.: Z Naturforsch 44a(1989),125
5. Litzistorf, G; Sengupta, S.; Lucken, E.A.C.: J Mol Struc 83(1982),285