GUTOWSKI, H.; NIENABER, U.; SANDTNER, G.; WEBER, J. Heat transfer during liquefaction and freezing-out of air in contercurrent-heatexchangers for helium-purification. ФІЗИКА НИЗЬКИХ ТЕМПЕРАТУР, Харків, Україна, v. 16, n. 5, p. 542–544, 1990. Disponível em: http://80.92.230.95/index.php/fnt/article/view/f16-0542e. Acesso em: 11 лис. 2025.