U.S. National Archives (Record Group 104 [Denver], Sequence 47, Letters from the Director) Público Deposited
National Archives series description: This series consists of copies of letters sent by the Superintendent of the U.S. Mint, Denver. The letters were written by Superintendent Gruber, and relate to administrative and operational issues. Many were directed to the Superintendent of the U.S. Mint, Philadelphia, and the Department of the Treasury.
The NARA transfer number for this series is 8KRA-104-84-47.
National Archive catalog record is at https://catalog.archives.gov/id/2619207. See also the National Archives & Records Administration numismatic finding aids at https://nnp.wustl.edu/library/archivedetail/538870.