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pubmed:abstractText |
Long-term follow-up studies sometimes rely on retrospective identification of the cohort to be followed. Few such studies have been conducted, however, that rely on very old source records, perhaps because of concern that identification and location of a cohort based on very old records would not be feasible.
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pubmed:affiliation |
Program in Epidemiology, Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, M4-B874, PO Box 19024, Seattle, WA 98109-1024, USA.
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