1. W. Hanle, Z. Phys. 30, 93 (1924).
2. A. G. Petrashen’, V. N. Rebane, and T. K. Rebane, Opt. Spektrosk. 70(4), 730 (1991) [Opt. Spectrosc. 70, 424 (1991)].
3. S. A. Kazantsev, A. G. Petrashen’, N. T. Polezhaeva, et al., Opt. Spektrosk. 69(5), 983 (1990) [Opt. Spectrosc. 69, 582 (1990)].
4. A. A. Radtsig and B. M. Smirnov, Reference Data on Atoms, Molecules, and Ions (Énergoatomizdat, Moscow, 1986; Springer-Verlag, Berlin, 1985).
5. I. I. Sobelman, Atomic Spectra and Radiative Transitions (Fizmatgiz, Moscow, 1963; Springer-Verlag, Berlin, 1979).