1. M. A. Bogdasarov, Fossil Resins in Northern Eurasia (Brest State Univ., Brest, 2005) [in Russian].
2. V. I. Katinas, Amber and Amber-Bearing Deposits in the Southern Baltic Region (Mintis, Vilnius, 1971) [in Russian].
3. S. S. Savkevich, “Physical Method for the Identification of the Amber-Type Resins,” in Mineralogy for National Economy (Nauka, Leningrad, 1987), pp. 246–247 [in Russian].
4. S. S. Savkevich, Amber (Nedra, Leningrad, 1970) [in Russian].
5. T. N. Sokolova, Candidate’s Dissertation in Geology and Mineralogy (Leningrad State Univ., Leningrad, 1987).