The LancetVolume 309, Issue 8010, 5 March 1977, Page 523WORKING SHIFTSAuthor links open overlay panelShow moreShareCitehttps://doi.org/10.1016/S0140-6736(77)91382-4Get rights and contentRecommended articlesReferences (4)P.C. Ganguli et al.Nature(1972)There are more references available in the full text version of this article.Cited by (0)View full textCopyright © 1977 Published by Elsevier Ltd.