Out-of-print textbooks that should be reprinted

One of the things I'm looking into doing is beginning a Dover-like publishing company for putting out-of-print textbooks back into print in nice, cheap editions for students. So I'd like to ask the mathematicians here who are aware of such books:

What books that are out of print would you like to see republished in such editions—books for which you think it's a tragedy that they are out of print?

I think it's a good question for professional mathematicians and would form the basis for the beginnings of my book line. No limit on how many you'd like to suggest.

I have a ton of such books, but I'll kick it off with the two books I think it's tragic are out of print:

Functional Analysis, 2nd. ed. by L.V.Kantorovich and G.P. Akilov.

Notes On Differential Geometry by Noel J.Hicks. (Yes, I know there's a PDF of it floating around online, but a lot of us would like an actual physical book.)

Solution 1:

Theory of Numbers: A Text and Source Book of Problems, Andrew Adler, John E. Coury.

I love this book, but unfortunately it is out of print!

Solution 2:

Basic Techniques of Combinatorial Theory by Daniel I.A. Cohen. This books offers a clear exposition on basic undergraduate topics in combinatorics, contains multiple proofs of many theorems and has some of the best exercises I have encountered. It was a real pleasure to learn from.

Solution 3:

The Complex Analytic Theory of Teichmüller Spaces, by Subhashis Nag.

I know many people who have been looking for this great book.