Friedman, Samuel R., Milagros Sandoval, Pedro Mateu-Gelabert, Diana Rossi, Marya Gwadz, Kirk Dombrowski, Pavlo Smyrnov, Tetyana Vasylyeva, Enrique R. Pouget, and David Perlman. "Theory, measurement and hard times: some issues for HIV/AIDS research." AIDS and behavior 17, no. 6 (2013): 1915-25.