Haynes RB, Sackett DL, Guyatt GH, et al. Clinical epidemiology: how to do clinical practice research. 3rd edition. Philadelphia, PA: Lippincott Williams & Wilkins, 2006.
Haynes RB, Sackett DL, Guyatt GH, et al. Clinical epidemiology: how to do clinical practice research. 3rd edition. Philadelphia, PA: Lippincott Williams & Wilkins, 2006.