We found a matchYour institution may have access to this item. Find your institution then sign in to continue.TitleBiologic synergism and parallelism.AuthorsDarroch JPublicationAmerican journal of epidemiology, 1997, Vol 145, Issue 7, p661ISSN0002-9262Publication typearticleDOI10.1093/oxfordjournals.aje.a009164