Comparison of seven protocols to identify fecal contamination sources using escherichia coli - Fenger, Terry W.; Hagedorn, Charles.; Hyer, Kenneth E.; Kator, Howard.; Lukasik, Jerzy.; Mathes, Melvin V.; O'Brien, Tara L.; Samadpour, Mansour.; Stoeckel, Donald M.; Strickler, Kriston M.; Wiggins, Bruce A.