U.S. National Archives (Record Group 104, Entry 14, Anonymous Letters) Pubblico Deposited
National Archives entry description: ANONYMOUS LETTERS RECEIVED BEFORE 1900. Anonymous letters received by the Director or Superintendent of the Mint. It appears that at one time these letters were a part of the correspondence described in entry 1. A few letters contain suggestions concerning fiscal policy or the operations of the mint. Arranged in rough chronological order. This material was scanned in Philadelphia under the direction of R.W. Julian, operating through a grant from the Central States Numismatic Society.
National Archives catalog link: https://catalog.archives.gov/id/564640. See also the National Archives & Records Administration numismatic finding aids at https://nnp.wustl.edu/library/archivedetail/538870.