Stojanova, Violeta, and Goše Petrov. 2013. “Foraminifers and Nannofossils from Upper Flysch Lithozone in the Tikveš Paleogene Basin, Republic of Macedonia”. Geologica Macedonica 26 (1), pp.87–98. https://js.ugd.edu.mk/index.php/GEOLMAC/article/view/654.