Trien, Hoang, 		Nhan, Nguyen, 		Hung, Do, AND 		Bau, Nguyen.
" The dependence of the parametric transformation coefficient of acoustic and optical phonons in doped superlattices on concentration of impurities" <em>VNU Journal of Science: Mathematics - Physics</em> [Online], Volume 25 Number 2 (15 June 2009)