Todorova, S.
Naydenov, A.
Velinova, R.
Kolev, H.
Larin, A. V.
Stoyanova, D.
Shopska, M.
Tenchev, K.
Stefanov, P.
Funding for this research was provided by:
Bulgarian National Science Fund (DFNI/Russia 01/1)
Russian Foundation for Basic Research (17-53-18026-Bolg_а)
Article History
Received: 12 October 2018
Accepted: 8 December 2018
First Online: 19 December 2018