Bermejo-Martin, Jesus F., Raquel Almansa, and Raul Ortiz de Lejarazu. 2013. “Weakened Immunity in Aged Hosts With Comorbidities As a Risk Factor for the Emergence of Influenza A H7N9 Mutants”. The Journal of Infection in Developing Countries 7 (06):497-98. https://doi.org/10.3855/jidc.3810.