1 2 Brewer, M (2000). Reis, H; Judd, C (บ.ก.). Research Design and Issues of Validity. Handbook of Research Methods in Social and Personality Psychology. Cambridge: Cambridge University Press.CS1 maint: uses editors parameter (link)
1 2 Shadish, W; Cook, T; Campbell, D (2002). Experimental and Quasi-Experimental Designs for Generalized Causal Inference. Boston: Houghton Mifflin.CS1 maint: uses authors parameter (link)
