1. “Inclusion Compounds”, eds J. L. Atwood, J. E. D. Davies and D. D. MacNicol, Academic Press, London 1984.
2. H. Davy, Phil. Trans. Roy. Soc. (London), 101 (1811) 1.
3. M. von Stackelberg, Naturwiss., 36 (1949) 327, 359.
4. M. von Stackelberg and H. R. Müller, Z. Electrochem., 58 (1954) 25.
5. K. A. Kavenvolden and M. A.McMenamin, U.S. Geol. Surv. Cire., (1980) 825.