Research index·Journal articleMonthly ProgramThe Sciences·1 Mar 1979DOI10.1002/j.2326-1951.1979.tb01324.xJournal articleMonthly ProgramThe Sciences · 1979 · SubscriptionDOI10.1002/j.2326-1951.1979.tb01324.xReadRead 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 discussionTopicsCitationComputer scienceInformation retrievalWorld Wide WebLibrary scienceRelated papersMoreDetailsPublished, publisher, issueSuggest a correction or report