License: CC-BY-NC-SA

The text requires students to be active learners — there are very few worked examples in the text, with there instead being 3-4 activities per section that engage students in connecting ideas, solving problems, and developing understanding of key calculus concepts; each section begins with motivating questions, a brief introduction, and a preview activity, all of which are designed to be read and completed prior to class; the exercises are few in number and challenging in nature.

The text focuses on the formal development of mathematics. Endorsed by the American Institute of Mathematics' Open Textbook Initiative.
License:

Author's website with study guides, solutions, videos, and supporting files:
https://sites.google.com/site/mathematicalreasoning3ed/

License: CC-BY-NC-SA

Topics include simulation modeling methods, case studies, exercises, and software tutorials.

Includes links to many resources; especially geared toward biology teachers and biology education majors.

Euro-centric, but some books/chapters are authored by faculty at places like MIT, Rice, etc.

Topics include introductory mathematics, calculus, real analysis, and statistics.

License: CC-BY-NC-SA

It does not assume previous coverage of Linear Algebra. The book includes applications from many disciplines, and integrates the use of the open-source computer algebra system Maxima throughout.