Ivanova, Mariana https://orcid.org/0000-0002-0441-3043
Manolova, Irena https://orcid.org/0000-0002-4905-6537
Miteva, Lyuba https://orcid.org/0000-0002-0028-7692
Gancheva, Rada https://orcid.org/0000-0001-5246-9247
Stoilov, Rumen https://orcid.org/0000-0002-6340-9650
Stanilova, Spaska https://orcid.org/0000-0003-1368-9081
Article History
Received: 14 August 2018
Accepted: 8 November 2018
First Online: 15 November 2018
Compliance with ethical standards
:
: The authors declare that there is no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study.