Authors
Stanislav Donchev
University of Shumen Bishop Konstantin Preslavski, Department of Chemistry, Faculty of Natural Sciences, Shumen, Bulgaria
Tsvetan V. Tsenov
University of Shumen Bishop Konstantin Preslavski, Department of Chemistry, Faculty of Natural Sciences, Shumen, Bulgaria
Christomir Christov
University of Shumen Bishop Konstantin Preslavski, Department of Chemistry, Faculty of Natural Sciences, Shumen, Bulgaria