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Image caption on page 95 of the book US National Library of Medicine: "Staff carefully analyzed individual articles to identify main concepts, and then assigned descriptors from a standard vocabulary known as the Medical Subject Headings (MeSH), which the library began publishing in 1960, to facilitate effective search and retrieval. Staff typed individual indexed citations on paper slips and then assembled the slips on a board to be photographed and printed as an index to current medical research."
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