1. Treatment of drug abuse;Anglin,1990
2. The effectiveness of methadone maintenance treatment: Clients, programs, services, and outcome;Ball,1991
3. An investigation of the robustness of the t test to unit of analysis violations;Blair;Educational and Psychological Measurement,1983
4. Hierarchical linear models: Applications and data analysis methods;Bryk,1992
5. HLM: Hierarchical linear and nonlinear modeling with the HLM/2L and HLM/3L programs;Bryk,1996