Chadaev, V. Ye., I. N. Kuchkov, I. V. Cherkashina, K. A. Goltsev, and I. V. Dobrunova. 2005. “Morphological and Functional Characteristics of Human Spermatozoa After Cryopreservation under Ultrarapid Cooling”. Problems of Cryobiology and Cryomedicine 15 (4):665-70. https://cryo.org.ua/journal/index.php/probl-cryobiol-cryomed/article/view/1216.