1. See for instance: Schmid, E.W., Ziegelmann, H.: The quantum mechanical three-body problem. Tracts in pure and applied physics. Braunschweig: Vieweg 1974
2. Hetherington, J.H., Schick, L.H.: Phys. Rev. B137, 935 (1965) see also Ref. 1
3. Glöckle, W., Offermann, R.: Phys. Rev.16, 2039 (1977)
4. Baker, G.A.: Essentials of Padé-Approximants. New York: Academic Press 1975
5. Malfliet, R.A., Tjon, J.A.: Nucl. Phys. A127, 161 (1969)