Pettigrew, A. (1989). Longitudinal Methods to Study Change: Theory and Practice. Routledge.
Lua i Stíl Chicago (17ú heag.)Pettigrew, A. Longitudinal Methods to Study Change: Theory and Practice. Routledge, 1989.
Lua MLA (9ú heag.)Pettigrew, A. Longitudinal Methods to Study Change: Theory and Practice. Routledge, 1989.
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