N. F. Shul’ga, A. S. Bakai, S. V. Peletminskii, Y. V. Slyusarenko, A. A. Zheltukhin, and D. V. Uvarov, “To the 90-th Anniversary of Dmitrii Vasil’evich Volkov’s Birthday”, Ukr. J. Phys., vol. 60, no. 7, p. 675, Jan. 2019.