1. Sakai, A.; Kasahara, M.; Tatsuzaki, I.:J Phys Soc Jpn 47(1979),161
2. Burkert, P.K.; Eckel, M.F.:Z Naturforsch B Anorg Chem Org Chem 28(1973),379
3. O'Reilly, D.E.; Tsang, T.:J Chem Phys 46(1967),1291
4. Lee, K.; Sher, A.; Andersson, L.O.; Proctor, W.G.:Phys Rev 150(1966),168
5. Weulersse, J.M.; Virlet, J.; Rigny, P.:Mol Phys 38(1979),923