Hikari Ltd, P.O. Box 85
Rousse 7000, Bulgaria
Hikari Ltd, Vidin str. 40, office no. 3
Rousse 7012, Bulgaria
E. Minchev holds master's degree in physics from Sofia University and Ph.D degree in mathematics from Chiba University, Japan. He has specialized in mathematical sciences in Waseda University, Tokyo, Japan.
Plamena Yordanova graduated from Ruse University, Bulgaria with master's degree in engineering sciences.