1. K. A. Gschneidner, N. Kippenhan, O. D. McMasters; “Thermochemistry of the Rare Earths,” Rare Earth Information Center, Ames, Iowa 50010, Report # 1S-RIC-6.
2. K. A. Gschneidner, N. Kippenhan; “Thermochemistry of the Rare Earth Carbides, Nitrides, and Sulphides for Steelmaking.” Rare Earth Information Center, Ames, Iowa 50010, Report # IS-RIC-5.
3. J. A. Gibson and G. S. Harvey; “Properties of the Rare Earth Metals and Compounds,” Battelle Memorial Institute, Technical Report AFML-TR-65-430.
4. R. J. Leary et al; U. S. Department of Interior, Bureau of Mines, R.I. 7091, March 1968, p. 28.
5. H. A. Tucker, R. T. Coulehan and W. G. Wilson; “Rare Earth Silicide Additions to an Alloy Steel to Increase Toughness and Ductility,” U. S. Department of the Interior, Bureau of Mines, RI 7153, June, 1968.