Weichselbaum RR, Beckett MA, Vijayakumar S, Ahmed-Swan S, Dritschilo A, Schwartz JL, Moran WJ, Goldman ME, Tybor AG, Vokes EE, et al. Radioresistant tumor cell lines derived from head and neck radiation failures. Head Neck. 1989 Jul-Aug; 11(4):343-8.