[1] MARC 21 Format for Authority Data: Appendix A: Control Subfields (Network Development and MARC Standards Office, Library of Congress), Library of Congress Network Development and MARC Standards Office, 6/3/2021, 10:08:58 PM, 12/11/2022, 1:01:41 PM https://www.loc.gov/marc/authority/ecadcntf.html
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