Author I. Tzoulaki M. Molokhia V. Curcin M. Little C. Millett A. Ng R. Hughes K. Khunti M. Wilkins A. Majeed P. Elliott Year of Publication 2009 DOI 10.1136/bmj.b4731 DOIGoogle ScholarBibTeXEndNote X3 XMLEndNote 7 XMLEndnote taggedMarcRIS