1. P. Bonifazi, Astronomical and Astrophysical Trans., 22, 557 (2003).
2. P. Astone et al., Class. Quantum Grav., 19, 5449 (2002).
3. A. V. Gusev et al., Astronom. Zh., 74, Issue 2, 287 (1997).
4. Astrophysics, Quanta, and Relativity Theory [Russian translation], Mir, Moscow (1982).
5. P. Astone et al., Il Nuovo Cimento, 20C, No. 1, 9 (1994).