Takov, D.
Doychev, D. http://orcid.org/0000-0003-1109-6194
Pilarska, D.
Draganova, S.
Nedelchev, S.
Linde, A.
Funding for this research was provided by:
National Science Fund of Bulgaria (DO-02-251/2008)
Article History
Received: 13 July 2018
Accepted: 27 March 2019
First Online: 18 April 2019
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.