Authors
Dimitar Dimitrov
Institute of Oceanology, Bulgarian Academy of Sciences, Varna, Bulgaria
Banush Banushev
University of Mining and Geology “St. Ivan Rilski”, Studentski Grad, “Prof. Boyan Kamenov” Str, Sofia, Bulgaria
© 2021 Dimitar Dimitrov, Banush Banushev, published by Konstantin Preslavski University of Shumen
This work is licensed under the Creative Commons Attribution 4.0 License.