Minkin, Krasimir http://orcid.org/0000-0003-1203-2870
Gabrovski, Kaloyan
Sirakov, Stanimir
Penkov, Marin
Todorov, Yuri
Karakostov, Vasil
Dimova, Petia
Article History
Received: 6 January 2019
Accepted: 6 March 2019
First Online: 1 April 2019
Compliance with ethical standards
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the University Hospital “Saint Ivan Rilski” 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 conflict of interest.