BOEV, I.; TASEV, G.; SERAFIMOVSKI, D.; BOEV, B. VOLCANIC ACTIVITY IN THE KOŽUF MOUNTAIN AREA AND IMPLICATIONS FOR THE DISTRIBUTION OF RARE EARTH ELEMENTS IN DIATOMITE AND TRIDYMITE. Geologica Macedonica, v. 33, n. 1, p. 5-24, 17 Jun. 2019.