RT Journal Article SR Electronic T1 Of studies, syntheses, synopses, and systems: the ā€œ4Sā€ evolution of services for finding current best evidence JF Evidence Based Medicine JO Evid Based Med FD BMJ Publishing Group Ltd SP 36 OP 38 DO 10.1136/ebm.6.2.36 VO 6 IS 2 A1 Haynes, R Brian YR 2001 UL http://ebm.bmj.com/content/6/2/36.abstract AB