Winters J C, Jorritsma W, Groenier K H, Sobel J S, Meyboom-de Jong B, Arendzen H J
Department of Family Practice, University of Groningen, Ant Deusinglaan 4, 9713 AW Groningen, The Netherlands.
BMJ. 1999 May 22;318(7195):1395-6. doi: 10.1136/bmj.318.7195.1395.