1. S. Berko, F.L. Hereford: Rev. Mod. Phys.28, 299 (1956)
2. R.A. Ferrell: Rev. Mod. Phys.28, 308 (1956)
3. J. Lee, J.H. Green:Positronium Chemistry (Academic Press, New York 1964)
4. V.I. Goldanski: Atomic Energy Rev.6, 3 (1968)
5. J.A. Merrigan, J.H. Green, S.J. Tao: InPhysical Methods of Chemistry, ed. by A. Weissberger and B.W. Rossiter (Wiley, New York 1972) Vol. 1, Pt. IID