// <I>ICTTE 2020<D> : International coference on ''Technics, technologies and education 2020'', 4th-6th november 2020, Yambol, Bulgaria : IOP Conference series : Materials science and engineering, 1031, DOI:10.1088/1757-899X/1031/1/012014.
R. G. Rusev; P. Kazakov; A. Iliev;
M. S. Dimitrov и др.