1. NEW SAMPLER FOR THE COLLECTION, SIZING, AND ENUMERATION OF VIABLE AIRBORNE PARTICLES,
2. APHA ( 1989 ).Method 9215, Heterotrophic Plate Count, in Standard Methods for the Examination of Water and Wastewater, A. Greenberg , J. Conners , and D. Jenkins , eds. American Public Health Association , Washington , D.C. , pp. 789 – 793 .