theory of modern optical instruments : a reference book for physicists, manufacturers of optical instruments and for officers in the army and navy / by … Stereoscopic rangefinder : 3 M. base length Geodätische Instrumente : Nivellierungsinstrumente / Adolf Fennel Geodätische Instrumente : Nonien-Theodolite / Adolf Fennel handleiding Fotocellen en fotoelektrische Vÿô-meetinstrumenten / [samenst.: G. v.d. Lugt ; tek.: E.M. Nederlof]