Beck J D, Slade G, Offenbacher S
Department of Dental Ecology, Center for Oral and Systemic Diseases, School of Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Periodontol 2000. 2000 Jun;23:110-20. doi: 10.1034/j.1600-0757.2000.2230111.x.