Detection of norovirus and astrovirus mixed infections in stool samples of children with gastroenteritis from São Paulo, Brazil - Castilho, Juliana Galera; Racz, Maria Lucia Barbosa de Oliveira; Resque, H. R.; Munford, V.; Fagundes-Neto, U. (Congresso Instituto Ciências Biomédicas, IV, 2003)