Joint effects of intensity and duration of cigarette smoking on the risk of head and neck cancer: A bivariate spline model approach - Di Credico, Gioia; Matsuo, Keitaro; Brennan, Paul J.; Vilensky, Marta; Fernandez, Leticia; Curado, Maria Paula; Menezes, Ana; Daudt, Alexander W; Koifman, Rosalina; Wünsch Filho, Victor; Holcátová, Ivana; Edefonti, Valeria; et al. (Oral oncology, 2019)