Epidemiology and genetic variability of human metapneumovirus during a 4-year-long study in southeastern Brazil - Oliveira, Danielle B. L.; Durigon, Edison Luiz; Carvalho, Ariane C. L.; Leal, Andréa L.; Souza, Thereza S.; Thomazelli, Luciano M.; Moraes, Claudia Trigo Pedroso de; Vieira, Sandra Elisabete; Gilio, Alfredo Elias; Stewien, Klaus Eberhard (Journal of Medical Virology, 2009)