Levitan, S. A., & Wurzburg, G. K. (1979). Evaluating Federal social programs: An uncertain art. W.E. Upjohn Institute for Employment Research.
Lua i Stíl Chicago (17ú heag.)Levitan, Sar A., agus Gregory K. Wurzburg. Evaluating Federal Social Programs: An Uncertain Art. Kalamazoo, Mich: W.E. Upjohn Institute for Employment Research, 1979.
Lua MLA (9ú heag.)Levitan, Sar A., agus Gregory K. Wurzburg. Evaluating Federal Social Programs: An Uncertain Art. W.E. Upjohn Institute for Employment Research, 1979.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.