D. . Tiwawech, S. . Chindavijak, A. . Karalak, T. Ishida, and Y. Jarratwisrutpom, “Detection of GSTM1 Polymorphism in Patient with Nasopharyngeal Carcinoma by Real-Time PCR”, Siriraj Med J, vol. 60, no. 1, pp. 23–27, Jan. 2008.