Differential Viral Fitness Between H1N1 and H3N8 Avian Influenza Viruses Isolated from Mallards (Anas platyrhynchos)., Ferreira, Helena Lage, Vangeluwe Didier, Van Borm Steven, Poncin Olivier, Dumont Nathalie, Ozhelvaci Orkun, Munir Muhammad, van den Berg Thierry, and Lambrecht Bénédicte , Avian Dis, 2015 Dec, Volume 59, Issue 4, p.498-507, (2015)