8Cheng WM,Chan KH,Chen HL,et al. Assessing the risk of nasopha- ryngeal carainoma on the basis of EBV antibody spectrum [ J ]. Int J Cancer,2002,97 (4) :489 -492.
9Leong JL, Fong KW, Low WK. Factors contributing to delayed diagnosis in nasopharyngeal carcinoma. J LaryngolOtol, 1999, 113: 633-636.