ROVENCHAK, A. Effective mass of atom and the excitation spectrum in liquid helium-4 at T = 0 K. ФІЗИКА НИЗЬКИХ ТЕМПЕРАТУР, Харків, Україна, v. 29, n. 2, p. 145–148, 2003. Disponível em: https://fnt.ilt.kharkiv.ua/index.php/fnt/article/view/f29-0145e. Acesso em: 15 лис. 2024.