Perdana, R. F. “Transnasal Esophagoscopy Examination in Outpatient Unit, Department of Otorhinolaryngology Head and Neck Surgery, Dr. Soetomo Hospital, Surabaya”. Folia Medica Indonesiana, vol. 56, no. 1, Mar. 2020, pp. 75-81, doi:10.20473/fmi.v56i1.24616.