1. Department of Otorhinolaryngology - Head and Neck Surgery, Faculty of Medicine, Universitas Airlangga - Dr. Soetomo General Academic Hospital, Mayjen Prof. Dr. Moestopo street No 6-8 Surabaya, Indonesia.
2. Department of Otorhinolaryngology - Head and Neck Surgery, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia.