Li, Tiegang, and Ming Wang. “ CLINICAL MANIFESTATIONS SEEMED MORE SEVERE AMONG PATIENTS WITH ANTIBODY 4-FOLD OR A GREATER INCREASE IN TITER BOTH AGAINST pH1N1 AND AGAINST SEASONAL INFLUENZA THAN THOSE WHOSE ANTIBODY 4-FOLD OR GREATER INCREASE IN TITER WAS ONLY AGAINST ONE TYPE OF SEASONAL INFLUENZA ”. Revista Do Instituto De Medicina Tropical De São Paulo, vol. 56, no. 2, Apr. 2014, pp. 183-4, https://revistas.usp.br/rimtsp/article/view/78722.