Van Vleck, J.H.: J. Chem. Phys. 2, 20 (1934)
Moffitt, W.: Repts. Progr. Phys. 17, 173 (1954)
Voge, H.H.: J. Chem. Phys. 4, 581 (1936); 16, 984 (1948)
Hurley, A.C.: J. Chem. Phys. 28, 532 (1958)
Öpik, U.: Mol. Phys. 4, 505 (1961)
Anno, T.: Theoret. Chim. Acta (Berl.) 25, 248 (1972)
Craig, D.P., Thirunamachandran, T.: Proc. Royal Soc. (London) A303, 233 (1968)
Peterson, C., Pfeiffer, G. V.: Theoret. Chim. Acta (Berl.) 26, 321 (1972)
Companion, A.L., Ellison, F. O.: J. Chem. Phys. 28, 1 (1958)
Moore, C. E.: Natl. Bur. Std. (U.S.) Circ. No. 467 (1949)