GUTOWSKI, H., NIENABER, U., SANDTNER, G., & WEBER, J. (1990). Heat transfer during liquefaction and freezing-out of air in contercurrent-heatexchangers for helium-purification. ФІЗИКА НИЗЬКИХ ТЕМПЕРАТУР, 16(5), 542–544. вилучено із https://fnt.ilt.kharkov.ua/index.php/fnt/article/view/f16-0542e