MANDAL, D K, et al. “Cyto-Morphological Abnormalities and Cell Membrane Integrity of Frozen-Thawed Spermatozoa of Frieswal Bulls and Their Relationship With Fertility”. The Indian Journal of Animal Reproduction, vol. 28, no. 2, Dec. 2007, pp. 30-33, https://acspublisher.com/journals/index.php/ijar/article/view/4987.