Ndifon, Wilfred, Jonathan Dushoff, and Simon Levin. (2009) 2009. “On the Use of Hemagglutination-Inhibition for Influenza Surveillance: Surveillance Data Are Predictive of Influenza Vaccine Effectiveness.”. Vaccine 27 (18): 2447-52. doi:10.1016/j.vaccine.2009.02.047.