E. Velikova, Faculty of Mathematics and Informatics, Sofia University,
N. Zlateva, Faculty of Mathematics and Informatics, Sofia University,
A. Soskova, Faculty of Mathematics and Informatics, Sofia University,
W. Gushev, Faculty of Mathematics and Informatics, Sofia University,
B. Draganov, Faculty of Mathematics and Informatics, Sofia University,
E. Stefanova, Faculty of Mathematics and Informatics, Sofia University,
O. Georgieva, Faculty of Mathematics and Informatics, Sofia University,
A. Angelov, Faculty of Mathematics and Informatics, Sofia University,
S. Dimitrov, Faculty of Mathematics and Informatics, Sofia University,
A. Ivanova, Faculty of Chemistry and Pharmacy, Sofia University,
H. Gagov, Faculty of Geology and Geography, Sofia University,
I. Stefanov, Faculty of Physics, Sofia University