APA-referens (7:e uppl.)

Rothwell, P. (2006). Factors that can affect the external validity of randomised controlled trials.

Chicago-referens (17:e uppl.)

Rothwell, P. Factors That Can Affect the External Validity of Randomised Controlled Trials. 2006.

MLA-referens (9:e uppl.)

Rothwell, P. Factors That Can Affect the External Validity of Randomised Controlled Trials. 2006.

Varning: dessa hänvisningar är inte alltid fullständigt riktiga.