Spatial and temporal distribution of fecal coliforms, coliphages, moulds and yeasts in freshwater at the semi-arid tropic northeast region in Brazil (Paraíba state) - Ceballos, Beatriz Susana Ovruski de; Lima, Edeltrudes O. de; König, Annemarie; Martins, Maria Therezinha (Revista de Microbiologia, 1995)