Brief History of the Gruen Watch CompanyCreated By: Robert Dietrich Gruen Publisher: Indianapolis: KenRo Printing Company, 1991
Historical Facts about the Development of Gruen Watchmakers GuildCreated By: Gruen, Frederick G Source/Publisher: </em>In<em> Buckeye Horology. Edited by James W. Gibbs, 83-91. Columbia, PA: The Art Crafters, 1971
Priceless Possession of A FewCreated By: Fuller, Eugene T Source/Publisher: Bulletin Supplement of the National Association of Watch and Clock Collectors 10 (1974)
