Sinnyovsky, Dimitar http://orcid.org/0000-0001-6911-1831
Sachkov, Dimitar
Tsvetkova, Iliyana
Atanasova, Nadezhda
Funding for this research was provided by:
Bulgarian National Science Fund (Russia 02/14)
Article History
Received: 21 April 2019
Accepted: 22 January 2020
First Online: 13 February 2020