Elements of Programming Interviews: The Insiders' Guide
Adnan Aziz & Tsung-Hsien Lee & Amit Prakash
Proof and the Art of Mathematics: Examples and Extensions
Joel David Hamkins
Reading, Writing, and Proving: A Closer Look at Mathematics
Ulrich Daepp & Pamela Gorkin
Calculus
Gilbert Strang
Computers and Intractability: A Guide to the Theory of NP-completeness
Michael R. Garey & David S. Johnson