Feder G, Eccles M, Grol R, Griffiths C, Grimshaw J
Department of General Practice and Primary Care, St Bartholomew's and the Royal London Medical College, Queen Mary and Westfield College, London E1 4NS.
BMJ. 1999 Mar 13;318(7185):728-30. doi: 10.1136/bmj.318.7185.728.