Some links to informations related to optimization:
These books are free of access (we can find these books on the web site of the author most of the time).
S. Boyd, "Convex Optimization"
Original link to this book: http://www.stanford.edu/~boyd/cvxbook/
C. T. Kelley, "Iterative Methods for Linear and Nonlinear equations", SIAM
Original link to this book: http://www.siam.org/books/textbooks/fr16_book.pdf
C. T. Kelley, "Iterative Methods for Optimization", SIAM
Original link to this book: http://www.siam.org/books/textbooks/fr18_book.pdf