1. 1. V.M. Bondar, A.G. Sarbei, and P.M. Tomchuk, Fiz. Tverd. Tela 44, 1540 (2002).
2. 2. P.M. Tomchuk, Ukr. Fiz. Zh. 49, 681 (2004).
3. 3. V.M. Bondar and N.F. Chernomorets, Ukr. Fiz. Zh. 48, 51 (2003).
4. 4. P.M. Tomchuk and V.M. Bondar, Ukr. Fiz. Zh. 53, 668 (2008).
5. 5. P.M. Tomchuk, V.M. Bondar, and O.E. Levshyn, Ukr. Fiz. Zh. 59, 507 (2014).