Most useful books for a math undergrad

What are the most useful books an undergraduate in math should read? I found Alock's "How to study as a math major" and "how to study for a math degree" very useful. Are there any other good readings before starting a math degree (or any other material which may come in handy, like shaum's mathematical handbook of formulas and tables?)?

[EDIT: can you suggest some readings to prepare for physics courses that will be included in the degree too?]

[EDIT_2: Thank you for your answers, but I was rather searching something about how to get started with university math or some useful book that can be used during the degree as an "help" (e.g.amazon.co.uk/Study-Mathematics-Degree-Lara-Alcock/dp/0199661324 and amazon.com/Schaums-Outline-Mathematical-Handbook-Formulas/dp/… ). Can you help me?]

Solution 1:

For a list of great books, see The Mathematics Autodidact’s Aid.

Solution 2:

The most comprehensive math bibliography which has been around for quite some time http://www.ocf.berkeley.edu/~abhishek/chicmath.htm

Solution 3:

Came here for the same purpose. A list of introductory maths books including Alcock's: http://www.moremathsgrads.org.uk/maths-books.html

Solution 4:

Shaum's is better for physics than for mathematics (for physics it is invaluable), at least that is what I found. It really depends on what your focus is, it seems like you would be best served by a good applied math book to go along with physics (I would also suggest getting really good at programming and statistics if you are doing mathematical physics). But another student would be better suited to a book more loaded towards number theory (I do not know of any at an undergrad level), or mathematical history.