Motivation and context of concurrent stimulant and opioid use among persons who use drugs in the rural United States: a multi-site qualitative inquiry

R. J. Fredericksen, R. Baker, A. Sibley, A. T. Estadt, D. Colston, L. S. Mixson, S. Walters, J. Bresett, X. A. Levander, G. Leichtling, T. Davy-Mendez, M. Powell, T. J. Stopka, M. Pho, J. Feinberg, J. Ezell, W. Zule, D. Seal, H. L.F. Cooper, B. M. WhitneyJ. A.C. Delaney, H. M. Crane, J. I. Tsui