Retropharyngeal Node Metastasis in Cancer of the Oropharynx and Hypopharynx: Analysis of Retropharyngeal Node Dissection Regarding Preoperative Radiographic Diagnosis.Koji Okumura, Takashi Matsuzuka, Hidehiro Matsuura et al.|Nippon Jibiinkoka Gakkai Kaiho|1998Cited by 19