• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Logo of brmedjBMJ helping doctors make better decisionsSearchLatest content
Br Med J. May 10, 1969; 2(5653): 387–389.
PMCID: PMC1983233


Get a printable copy (PDF file) of the complete article (1.0M).

Images on this page

Click on the image to see a larger version.

Articles from British Medical Journal are provided here courtesy of BMJ Publishing Group