Lethal factor to mice produced by Escherichia coli isolated from chickens with swollen head syndrome - Salvadori, Márcia Regina; Chudzinski-Tavassi, Ana Marisa; Baccaro, Maria Regina; Ferreira, Claudete Serrano Astolfi; Ferreira, Antonio José Piantino; Prado-Franceschi, Júlia; Yano, Tomomasa (Microbiology and Immunology, 2002)