Kanalev, Kostadin, et al. “LABORATORY INDICES OF THE CAPACITY OF THE BLOOD TO TRANSPORT OXYGEN AT NORMAL AND HIGH ALTITUDE IN ATHLETES AND PEOPLE WITH HIGH LEVEL PHYSICAL ACTIVITY”. KNOWLEDGE - International Journal , vol. 69, no. 4, Apr. 2025, pp. 783-7, https://ojs.ikm.mk/index.php/kij/article/view/7299.