1. F. S. GOULDING, J. M. JAKLEVIC, Ann. Rev. Nucl. Sci., 23 (1973) 45.
2. The Radiochemical Centre, Radioactive Low Energy Photon Sources, Technical Bulletin 72/6, 1972.
3. Amersham/Searle Corporation, Research Products Catalog, 1975.
4. The Radiochemical Centre, Mössbauer Sources, Technical Bulletin 75/4, 1975.
5. New England Nuclear, Catalog 76, 1976.