1. Stark J (1914) Ann Phys 43:965
2. Bethe HA, Salpeter EE (1957) Quantum mechanics of one- and two-electron atoms. Springer, Berlin
3. Landau LD, Lifshitz EM (1977) Quantum mechanics. Pergamon, Oxford
4. Stebbings RF, Dunning FB (eds) (1983) Rydberg states of atoms and molecules. Cambridge University Press, Cambridge
5. Nayfeh MN, Clark CW (eds) (1984) Atomic excitation and recombination in external fields. NBS, Gaithersburg