A few suggestions (though given the size of the sample, hard to be sure):

http://www.myfonts.com/fonts/font-fabric/solomon-sans/
http://www.myfonts.com/fonts/durotype/aspira/
http://www.myfonts.com/fonts/fontbureau/fb-nobel/
http://www.myfonts.com/fonts/layarbahtera/universal-doomsday/
http://www.myfonts.com/fonts/fontfont/mark/
http://www.myfonts.com/fonts/typesgal/barq/bold/

Close, but the the G terminates parallel to the baseline as does the valley of the M.

Thank you though, super close, it really is just those two letterforms holding things back.

Now this is really killing me! haha

Another similar:
http://fontfabric.com/code-pro/

Other than, obviously, this:
http://www.myfonts.com/fonts/itc/avant-garde-gothic/

Code pro looks really similar, the M is certainly there, as well as the G. Avante Garde Gothic's M is still on the baseline.

I am going to see if I can pick the book up today, maybe check the colophon.

*edit: Spoke too soon, the bowls of the 'P' and 'R' are the wrong proportion and the 'I' has feet. The search continues...

Can't identify it either and even with a better sample.
Only one alternative: Platform (main difference on /M vertex) and Regular

EDIT: thanks Don for correction.

With the exception of Universal Doomsday and Barq, all the options I gave you have an M that terminates parallel to and above the baseline (look at the the heavier weights, not the roman), and a G that terminates parallel to the baseline.

Platform's G doesn't match.

Here's a larger image of the book:

If we can't find a match, you might try to reverse engineer the font.
You could use Code Pro Bold, perhaps with minor adjustments, for capital letters like _C_, _G_ [raise bar and top terminal], _M_, _W_. and something like Platform Bold for letters like _R_ [widen bowl slightly] and _P_ [ditto]. The remaining capital letters, with the exception of _S_ [which differs from the title] could be taken from either font and width adjusted to match. As for _S_, Nobel Bold and Benton Sans Bold seem to have a match.
As for the lower case, the letters are too small to make a specific suggestion, other than to note that it has a two story _g_ with an upper bowl that seems slightly larger than the lower bowl that descends only slightly below the base and is not separated from the upper bowl, which may have an ear at 2 p.m. Could use _s_ from Nobel or Benton Sans
Glyph capital height of the component fonts would need to be standardized and, if the stroke width of the Bold is not identical, the stroke width of one or the other should be adjusted.
Minor point, based on the umlaut, all punctuation should be in square format. See for example Benton Sans.
Don