An Open Textbook (Michael Corral)
Elementary Calculus by Michael Corral covers single-variable calculus (Calculus I and II): limits, derivatives, integrals, series, and applications.
This is the web edition of the open textbook by Michael Corral, originally published at mecmath.net/calculus and also available on LibreTexts (Elementary Calculus 2e), licensed under the GNU Free Documentation License 1.3.