1. N. Rosen, P.M. Morse, Phys. Rev. 42, 210 (1932)
2. F. Büyükkiliç, H. Eg, Theor. Chim. Acta 98, 192 (1997)
3. H. Eg, Phys. Scr. 60, 195 (1999)
4. C. Grosche, F. Steiner, J. Math. Phys. 36, 2354 (1998)
5. C. Grosche, F. Steiner, Handbook of Feynman Path Integrals, Springer Tracts Mod. Phys., Vol. 145 (Springer-Verlag, Berlin, 1998) p. 99