2) Sadé J, et al: Secretory otitis media and the nature of the mucociliary system. Acta Otolaryngol (Stockh) 70: 351-357, 1970.
3) Lim DJ, et al: Ultrastructure of the Eustachian tube and middle ear mucosa in the guinea pig. Acta Otolaryngol (Stockh) 63: 425-444, 1967.
4) Hentzer E: Ultrastructure of the normal human middle ear, mastoid cavities, and Eustachian tube. Ann Otol Rhinol Laryngol 79: 1143-1157, 1970.
5) Lim DJ, et al: Secretory activity of normal middle ear epithelium: Scanning and transmission electron microscopic observation. Ann Otol Rhinol Laryngol 80: 319-329, 1971.