Magdalena Cerda, David Vlahov, Melissa Tracy and Sandro Galea
Addiction 103 ( 8 ): 1296 - 1307 , 2008
Amy S. B. Bohnert, Marta R. Prescott, David Vlahov, Kenneth J. Tardiff and Sandro Galea
Addiction 105 ( 6 ): 1049 - 1054 , 2010