1. See paper by J.D. Cashion in this proceedings.
2. A.V. Dolenko, B.G. Egiazarov, L.V. Isakov, V.I. Goldanskii, E.F. Makarov, and V.A. Trukhtanov, U.S. Patent No. 3, 597, 615 (1971).
3. H. Topsøe, B.S. Clausen and S. Mørup, See these Proceedings.
4. T. Zemcik and S. Havlicek, Proceedings of the International Conference on Mossbauer Spectroscopy (Bucharest, Romania) Vol.1, 405, 1977.
5. F.E. Huggins, G.P. Huffman, and G.R. Dunmyre, Proceedings of the Conference on Industrial Applications of the Mossbauer Effect, Hawaii, Dec. 1984.