Ivan Zenev
From the Department of Otolaryngology, Head and Neck Surgery, Queen Yoanna University Hospital of Sofia, Sofia, Bulgaria
Emil Zenev
the Department of Otolaryngology, Head and Neck Surgery, Zentralklinikum Augsburg, Germany
Nikolaf Sapundzhiev
and the Clinic of Otorhinolaryngology, St Marina University Hospital of Varna, Varna, Bulgaria
Mario Milkov
and the Clinic of Otorhinolaryngology, St Marina University Hospital of Varna, Varna, Bulgaria
Dimitrav Marev
and the Clinic of Otorhinolaryngology, St Marina University Hospital of Varna, Varna, Bulgaria