SOKOLOV, S. Variational approach to the problem of energy spectrum of surface electrons over liquid-helium film. ФІЗИКА НИЗЬКИХ ТЕМПЕРАТУР, Харків, Україна, v. 30, n. 3, p. 271–275, 2004. DOI: 10.1063/1.1645177. Disponível em: http://fnt.ilt.kharkov.ua/index.php/fnt/article/view/f30-0271e. Acesso em: 8 трав. 2024.