Boev, Ivan, Goran Tasev, Dalibor Serafimovski, and Blazo Boev. 2019. “VOLCANIC ACTIVITY IN THE KOŽUF MOUNTAIN AREA AND IMPLICATIONS FOR THE DISTRIBUTION OF RARE EARTH ELEMENTS IN DIATOMITE AND TRIDYMITE”. Geologica Macedonica 33 (1), 5-24. https://js.ugd.edu.mk/index.php/GEOLMAC/article/view/3025.