Bogdanov, K., and J. Kuncheva. “EPITHERMAL GOLD MINERALIZATION IN THE KRASSEN DEPOSIT, PANAGYURISHTE ORE DISTRICT, BULGARIA”. Geologica Macedonica, Vol. 31, no. 2, Dec. 2017, pp. 107-16, https://js.ugd.edu.mk/index.php/GEOLMAC/article/view/1953.