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Folia Medica 61(4): 540-544
doi:
10.3897/folmed.61.e47957
Received:
07 Nov 2018 | Approved:
06 Jun 2019 | Published:
31 Dec 2019
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Authors
Roman E. Tashev
- Corresponding author
Medical University of Sofia, Sofia, Bulgaria

Medical University - Pleven, Pleven, Bulgaria
Medical University - Varna, Varna, Bulgaria
Conflict of interest
The authors have declared that no competing interests exist.
This is an open access article distributed under the terms of the CC0 Public Domain Dedication.