Mathematics
Abstract Algebra: Abstract and Applications - An open algebra textbook for one or two-semester undergraduate course in abstract algebra.
Active Calculus 2.0 - A popular open Calculus textbook. More recent editions are listed in the American Institute of Mathematics link to the right of this page.
American Institute of Mathematics - List of approved open textbooks. A list of open textbooks that meet the evaluation criteria set by the AIM editorial board.
A First Course in Linear Algebra -Begins with systems of linear equations, then covers matrix algebra, before taking up finite-dimensional vector spaces in full generality. The final chapter covers matrix representations of linear transformations, through diagonalization, change of basis and Jordan canonical form. Determinants and eigenvalues are covered along the way.
Convex Optimization - a resources designed for researchers, scientists or engineers who use mathematical optimization and operations research and many fields of science and engineering.
Introduction to Probability, Statistics, and Random Processes - An open access, peer-reviewed textbook intended for undergraduate as well as first-year graduate level courses on the subject.