APA aipamena

Black, N. (1996). Why we need observational studies to evaluate the effectiveness of health care. BMJ Group.

Chicago Style aipamena

Black, N. Why We Need Observational Studies to Evaluate the Effectiveness of Health Care. BMJ Group, 1996.

MLA aipamena

Black, N. Why We Need Observational Studies to Evaluate the Effectiveness of Health Care. BMJ Group, 1996.

Kontuz: berrikusi erreferentzia hauek erabili aurretik.