Hartmann & Braun 1-amp. hot-wire ammeter | National Museum of American History
Complete Catalogue of Electrical Measuring and Test Instruments Manufactured by Hartmann and Braun (Classic Reprint): Hartmann and Braun: 9781333433789: Amazon.com: Books
Hartmann and Braun | Science Museum Group Collection
Antique Hartmann & Braun Frankfurt DC Ampmeter | eBay
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Complete Catalogue of Electrical Measuring and Test Instruments Manufactured by Hartmann and Braun (Classic Reprint): Hartmann and Braun: 9781333433789: Amazon.com: Books
Vintage - Hartmann & Braun Megaohm Electrical Resistance Meter (Not Te – CommunityWorx Thrift Online
Complete Catalogue Of Electrical Measuring And Test Instruments Manufactured By Hartmann & Braun: Electrical Engineers At Bockenheim-frankfort O/m: Hartmann und Braun, Bockenheim-Frankfurt: 9780343367015: Amazon.com: Books
Hartmann and Braun | Science Museum Group Collection