Redirecting you to http://www.ncbi.nlm.nih.gov/pubmed?term=DA%2C%20Gallagher%20KM%2C%20Finlayson%20T%2C%20Sanchez%20T%2C%20Lansky%20A%2C%20Sullivan%20PS.%20Surveillance%20of%20HIV%20risk%20and%20prevention%20behaviors%20of%20men%20who%20have%20sex%20with%20men%E2%80%94a%20national%20application%20of%20venue-based%2C%20time-space%20sampling.