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2. Kanwal R Letter of July 2, 2003, from R. Kanwal, Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Department of Health and Human Services, to Frank Morrison, Nebraska Popcorn. Clearwater, NE 2003.
3. Kanwal R, Martin S Letter of May 13, 2003, from R. Kanwal and S. Martin, Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Department of Health and Human Services, to Keith Heuermann, B.K. Heuermann Popcorn, Inc. Phillips, NE 2003.
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5. NIOSH: "Hazard evaluation and technical assistance report: American Pop Corn Company, Sioux City, IA." U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, OH, 2004.