Arriola CS, Brammer L, Epperson S, Blanton L, Kniss K, Mustaquim D, Steffens C, Dhara R, Leon M, Perez A, Chaves SS, Katz J, Wallis T, Villanueva J, Xu X, Abd Elal AI, Gubareva L, Cox N, Finelli L, Bresee J, Jhung M. Update: influenza activity - United States, September 29, 2013-February 8, 2014. MMWR Morb Mortal Wkly Rep. 2014 Feb 21; 63(7):148-54.