1. Doctoral Program, Faculty of Medicine, Universitas Airlangga, Jl. Mayjen Prof. Dr. Moestopo No.47, Pacar Kembang, Tambaksari, Surabaya, Jawa Timur 60132, Indonesia.
2. Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medicine, Universitas Airlangga, Dr Soetomo General Academic Hospital. Jl. Mayjen Prof. Dr. Moestopo No.6-8, Airlangga, Gubeng, Surabaya, Jawa Timur 60286, Indonesia.
3. Department of Otorhinolaryngology Head and Neck Surgery, Faculty of Medicine, Universitas Brawijaya, Veteran Malang Road, Malang, Jawa Timur 65145, Indonesia.