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\bibitem{Stark_etal1994} Stark, K., Leicht, A., \& M{\"u}ller, R. (1994). Characteristics of users of syringe vending machines in Berlin. \textit{Sozial- und Pr{\"a}ventivmedizin = Social and preventive medicine}, \textit{39}(4; 07/1994), 209--216.

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