Petrina, D., & Gredzhuk, V. (1996). On two models of interacting Bose gas: Bogolyubov`s model of superfluidity and Huang-Yang-Luttinger model. Математическая физика, анализ, геометрия, 3(3-4), 370–405. вилучено із http://mag.ilt.kharkiv.ua/index.php/mag/article/view/m03-0370e