HPV DNA, E6/E7 mRNA, and p16INK4a detection in head and neck cancers: a systematic review and meta-analysis, Ndiaye, Cathy, Mena Marisa, Alemany Laia, Arbyn M., Castellsagué Xavier, Laporte Louise, F Bosch Xavier, de Sanjosé Silvia, and Trottier Helen , The Lancet Oncology, Jan-11-2014, Volume 15, Issue 12, (2014)