The Archivist shall provide for the preservation, arrangement, repair and rehabilitation, duplication and reproduction (including microcopy publications), description, and exhibition of records or other documentary material transferred to him as may be needful or appropriate, including the preparation and publication of inventories, indexes, catalogs, and other finding aids or guides to facilitate their use. He may also prepare guides and other finding aids to Federal records and, when approved by the National Historical Publications and Records Commission, publish such historical works and collections of sources as seem appropriate for printing or otherwise recording at the public expense.