1. Gmelin Handbuch der Anorganischen Chemie;Weigel,1977
2. V.B. Parker, D.D. Wagman and W.H. Evans, Selected values of chemical thermodynamic properties, tables for the akaline-earth elements (elements 92 through 97 in the standard order of arrangement). National Bureau of Standards (U.S.), Tech. Note 270-6 (the appendix to Natl. Bur. Stand. (U.S.) Tech. Note 270-8 (1981) contains revised values for Tech. Note 270-6); earlier collation: F.D. Rossini, D.D. Wagman, W.H. Evans, S. Levine and I. Jaffe, Natl. Bur. Stand. (U.S.) Circ., 500 (1952).