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I tried to figure this one out, but no match so far: http://new.myfonts.com/WhatTheFont/forum/case/252212/
It resembles Futura, but the umlaut and i-dots are squared and the C has the same slants as Erbar-Grotesk. But it is not Erbar. The G-bar isn't slanted and the S is just like Futura's.
More samples can be found here: http://www.urbanrail.net/eu/ham/hh-gallery/hh-gallery.htm