// <I>Procееdings<D> of the 8th International Scientific Conference Achievements in Mechanical and Materials Engineering , Gliwice -Rydzyna- Pawlowice-Rokosowo, 24-27 October 1999.- Gliwice : Silesian Univ. of Technology, 1999, p. 531 - 534.
(1999)
R. Shishkov; G. Kirilova; D. D. Dochev;
M. Balcheva и др.