1. R. Latter, Phys. Rev.,99, 510, 1955.
2. S. Kobayashi undT. Taima, Table of the Exact Values of the T-F Function, Memoirs of the Faculty of Liberal Arts and Eduction, Kagawa, Japan, 1957.
3. H. A. Buchdahl, Ann. d. Physik.,17, 238, 1956.
4. N. F. Mott undH. S. W. Massey, The Theory of Atomic Collisions, Oxford, 2nd edition, 1950; p. 188.