Conev, Nikolay Vladimirov http://orcid.org/0000-0001-5267-0354
Donev, Ivan Shterev
Stoyanov, Dragomir Svetozarov
Article History
Received: 2 March 2018
Accepted: 5 September 2018
First Online: 15 September 2018
Compliance with ethical standards
:
: 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 Helsinki declaration and its later amendments or comparable ethical standards.”
: For this type of study, formal consent is not required.
: The authors declare that they have no conflicts of interest.