BMJ. 1992 Feb 29;304(6826):520-1. doi: 10.1136/bmj.304.6826.520.
BMJ (Clinical research ed.)
C McCollum
PMID: 1559052 PMCID: PMC1881382 DOI: 10.1136/bmj.304.6826.520 Free PMC Article
[No abstract available.]