Research index·Journal articleANNOTATIONSBMJ·31 Dec 1949DOI10.1136/bmj.2.4643.1518Journal articleANNOTATIONSBMJ · 1949 · SubscriptionDOI10.1136/bmj.2.4643.1518ReadRead at the publisherSaveCiteAdd to literature reviewPaywalledThe full text is at the publisherOpen it at the publisher to read it.Read at the publisherDiscussionAdd to the discussionTopicsComputer scienceWorld Wide WebInformation retrievalRelated papersMoreDetailsPublished, issue, issnSuggest a correction or report
