McDonald’s tries to reassure customers after deadly E. coli outbreak The Associated PressWhat we know about the McDonald’s E. coli outbreak investigation CNNMcDonald’s zeroes in on onions as the likely source of deadly E. coli outbreak NBC NewsWhere is the Quarter Pounder being removed? McDonald’s locations in 12 states impacted amid E. coli outbreak USA TODAYE. Coli Symptoms and Treatment: What to Know After McDonald’s Outbreak The New York Times