Shulskyi, M. “Cooperative Activity of Ivan Porytko from Rogatin”. Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies. Series Economical Sciences 21, no. 92 (May 11, 2019): 43-48. Accessed December 14, 2019. https://nvlvet.com.ua/index.php/economy/article/view/3681.