Authors
Karamfil Kalchev
University of Shumen, Faculty of Natural Sciences, Department of Biology, Shumen, Bulgaria
Iva Hristova
University of Shumen, Faculty of Natural Sciences, Department of Biology, Shumen, Bulgaria
Gergana Manova
University of Shumen, Faculty of Natural Sciences, Department of Biology, Shumen, Bulgaria
Lyubomir Manov
Vasil Levski National Military University, Artillery, Air Defense and CIS Faculty 1 Karel Shkorpil Str, Shumen, Bulgaria