Legionnaires' disease: description of an epidemic of pneumonia. - Fraser,D.W.; Tsai,T.R.; Orenstein,W.; Parkin,W.E.; Beecham,H.J.; Sharrar,R.G.; Harris,J.; Mallison,G.F.; Martin,S.M.; McDade,J.E.; Shepard,C.C.; Brachman,P.S. (N Engl J Med, 1977)