Authors
Zh. Cherneva
University Hospital of the Ministry of Internal Affairs – Sofia, Bulgaria
R. Cherneva
University Hospital for Respiratory Diseases “Sv. Sophia” – Sofia, Bulgaria
© 2020 Zh. Cherneva, R. Cherneva, published by Sofia Medical University
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.