NEW DATA ON THE GENUS SYRPHUS FABRICIUS, 1775 (DIPTERA: SYRPHIDAE) FROM THE BALKAN PENINSULA INCLUDING THE FIRST RECORD OF SYRPHUS NITRIDIFRONS BECKER, 1921. (2010). Acta Entomologica Serbica, 15(1), 91-105. http://147.91.73.126/index.php/aes/article/view/113