Incidence of human immunodeficiency virus type 1 dual infections in Amsterdam, The Netherlands, during 2003-2007. - van der Kuyl AC; Zorgdrager F; Jurriaans S; Back NK; Prins JM; Brinkman K; van Eeden A; Bakker M; Cornelissen M (Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2009)