@article{JETPL.109.320, title = {}, author = {, and , and Chulkov, E. V.}, journal = {JETP Lett.}, volume = {109}, issue = {5}, pages = {316}, year = {2019}, doi = {}, url = {http://jetpletters.ru/ps/dx/10.1134/S0370274X19050072}, note = {[Pisma v ZhETF 109, 320 (2019)]} }