Plansky, Vladimir, and Kalin Hristov. “SEASON OF DELIVERY, AGE OF FIRST FERTILISATION AND MILKING YIELD DURING THE FIRST LACTATION PERIOD OF HEIFERS”. TRADITION AND MODERNITY IN VETERINARY MEDICINE 5, no. 1 (June 24, 2020): 53–57. Accessed August 26, 2026. https://scij-tmvm.com/index.php/pub/article/view/117.