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: http://80.92.230.95/index.php/fnt/article/view/f29-0145e. Acesso em: 20 чер. 2025.