Genova, Ts.
Borisova, E.
Zhelyazkova, Al.
Penkov, N.
Vladimirov, B.
Terziev, I.
Semyachkina-Glushkovskaya, O.
Avramov, L.
Funding for this research was provided by:
Bulgarian National Science Fund (DFNI- B02/9/2014)
European Cooperation in Science and Technology (BM1205)
Ministry of Education and Science of the Russian Federation (17.488.2014/K)
Bulgarian Academy of Sciences (DFNP-183- A1)
World Federation of Scientists