Kalaydjiev, K.; Bulgarian Academy of Science - BAS
Lovchinov, V.; Bulgarian Academy of Science - BAS
Dimitrov, D.; Bulgarian Academy of Science - BAS
Kirov, M.; Bulgarian Academy of Science - BAS
Baychev, M.; Bulgarian Academy of Science - BAS
Popov, C.; Bulgarian Academy of Science - BAS
Radev, D. D.; Bulgarian Academy of Science - BAS
Marinov, M.; Bulgarian Academy of Science - BAS
Tumbalev, V.; Bulgarian Academy of Science - BAS
Radev, I.; University of Sofia