Computers and Intractability: A Guide to the Theory of NP-completeness
Michael R. Garey & David S. Johnson
How to Prove It: A Structured Approach
Daniel J. Velleman
Matrix Calculus (for Machine Learning and Beyond)
Alan Edelman, Steven G. Johnson
Advanced Engineering Electromagnetics
Constantine A. Balanis
Proximal Algorithms
Neal Parikh & Stephen P. Boyd & Now Publishers
Non-Convex Optimization for Machine Learning
Prateek Jain & Purushottam Kar