Beecher HK (July 1961). "Surgery as placebo. A quantitative study of bias". J Am Med Assoc 176: 1102–7. PMID13688614. PubMed, Pristupljeno 25. 4. 2013.
Beecher HK (July 1961). "Surgery as placebo. A quantitative study of bias". J Am Med Assoc 176: 1102–7. PMID13688614. PubMed, Pristupljeno 25. 4. 2013.