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