1. V. V. Kolpakov, Priroda, nos. 1–2, 58–61 (1951).
2. A. M. Portnov, Priroda, no. 11, 102–103 (1962).
3. A. M. Portnov, Zemlya i Vselennaya, no. 1, 77–81 (1993).
4. V. S. Antipin, A. N. Arsent’ev, and V. I. Voronin, et al., in Selected Issues of Astronomy (IGU, Irkutsk, 2006), pp. 163–168.
5. V. S. Antipin and A. M. Fedorov, Dokl. Earth Sci. 423, 1135–1139 (2008).