Hello,
Unfortunately, this is a known issue with the WorldCat UMD database. For titles that have a large number of items associated with them, like periodicals where the Libraries own lots of bound volumes and current issues, the call number and item availability do not show up. The Libraries have reported this problem to the WorldCat UMD database vendor, and they are working on it. In the meantime, for titles such as the New York Times, Nature, Science, or New England Journal of Medicine, you can search the Classic Catalog to see the call number and item availability.
Or, from the title screen in WorldCat UMD, click on the linked "University of Maryland, College Park," which will search the Classic Catalog for the title you are viewing.
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