1] Hannu Karttunen et al. (eds.): Fundamental Astronomy.
The best book covering all of astronomy (also for absolute beginners)
AND still going into a lot of detail for special work for people more 
involved AND presenting excellent graphics and pictures.

2] Pasachoff: Contemporary Astronomy 
Good introductory textbook for the nontechnical reader.  It gives a 
pretty good overview of the important topics, and it has good pictures.

3] Shu, Frank: The physical universe : an introduction to astronomy,

4] Astrophysical formulae : a compendium for the physicist and
astrophysicist / Kenneth R. Lang.
Here is everything you wanted to know (and more!) about astrophysical
formulae on a one-line/one-parargraph/one-shot deal.
Of course, the formulae come complete with references (a tad old, mind
you) but it's a must for everyone who's working in astronomy and
astrophysics. You learn something new everytime you flip through the pages!

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