1. Norris S, Atkins D, Bruening W, Fox S, Johnson E, Kane R, Morton SC, Oremus M, Ospina M, Randhawa G, Schoelles K, Shekelle P, Viswanathan M: Selecting observational studies for comparing medical interventions. Methods Guide for Effectiveness and Comparative Effectiveness Reviews. 2010, Rockville, MD: Agency for Healthcare Research and Quality
2. Berkman ND, Lohr KN, Ansari M, McDonagh M, Balk E, Whitlock E, Reston J, Bass E, Butler M, Gartlehner G, Hartling L, Kane R, McPheeters M, Morgan L, Morton SC, Viswanathan M, Sista P, Chang S: Grading the strength of a body of evidence when assessing health care interventions for the effective health care program of the Agency for Healthcare Research and Quality: an update. Methods Guide for Comparative Effectiveness Reviews. (Prepared by the RTI-UNC Evidence-based Practice Center under Contract No. 290- 2007-10056-I). AHRQ Publication No 13(14)-EHC130-EF. 2013, Rockville, MD: Agency for Healthcare Research and Quality
3. Chou R, Aronson N, Atkins D, Ismaila AS, Santaguida P, Smith DH, Whitlock E, Wilt TJ, Moher D: AHRQ series paper 4: assessing harms when comparing medical interventions: AHRQ and the effective health-care program. J Clin Epidemiol. 2010, 63: 502-512. 10.1016/j.jclinepi.2008.06.007.
4. Viswanathan M, Mohammed AT, Berkman ND, Chang S, Hartling L, McPheeters ML, Santaguida PL, Shamliyan T, Singh K, Tsertsvadze A, Treadwell JR: Assessing the risk of bias of individual studies in systematic reviews of health care interventions. Methods Guide for Comparative Effectiveness Reviews. AHRQ Publication No. 12-EHC047-EF. 2012, Rockville, MD: Agency for Healthcare Research and Quality
5. Norris SL, Moher D, Reeves BC, Shea B, Loke Y, Garner S, Anderson L, Tugwell P, Wells G: Issues relating to selective reporting when including non-randomized studies in systematic reviews on the effects of healthcare interventions. Res Synth Meth. 2013, 4: 36-47. 10.1002/jrsm.1062.