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HathiTrust volumes are identified via unique HathiTrust IDs. These alpha-numeric IDs track volumes across HathiTrust and HTRC systems. This volume of Jane Austen's letters has the volume ID hvd.32044021076179. When viewing a volume in the Digital Library, the volume ID can be found in the URL after "id=". The volume ID can be used to call metadata via the HathiTrust's Bibliographic API or to pull volume content via the HathiTrust's Data API. Additionally, the volume ID is often present in the file and/or directory name for content pertaining to a specific volume, and it also makes up the (pairtree) directory structure for volumes accessed via HathiTrust dataset requests or the HTRC Extracted Features Dataset.
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