SOURCES OF IONISING RADIATION AND THE NEGATIVE CONSEQUENCES OF RADIATION. TEACHING A PRACTICAL LESSON ON THE TOPIC OF THE EARTH’S NATURAL RADIATION BY THE «CLUSTER» METHOD OF PEDAGOGICAL TECHNOLOGIES IN MEDICAL HIGHER EDUCATION INSTITUTIONS. ReFocus [Internet]. 2023 Jun. 5 [cited 2026 Sep. 11];2(5):16-21. Available from: https://refocus.uz/index.php/rf/article/view/183