The Illustrated Professional Dictionary of Horology is a standard work in the world of watchmaking. It contains nearly 5,000 definitions of watchmaking or related terms. Articles are supplemented by a thousand illustrations of components or tools.
The work, often referred to today as the Berner Dictionary, after its author, is also a valuable translation tool. It is reproduced in full in French, English, German and Spanish.
The electronic version of the dictionary is available here.