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Larsen, P. O. & von Ins, M.
The rate of growth in scientific publication and the decline in coverage provided by Science Citation Index
Scientometrics, 2010, 84, 575-603

Article (small1973cocitation)
Small, H.
Co-citation in the scientific literature: A new measure of the relationship between two documents
Journal of the American Society for Information Science, Wiley Subscription Services, Inc., A Wiley Company, 1973, 24, 265-269