Abstract Algebra: Theory and Applications and The Ordinary Differential Equation Project are open source textbooks licensed with a GNU Free Documentation License (GFDL). Since both textbooks are written in PreTeXt, a lightweight XML application, the textbooks can be produced in different formats such as print, HTML, and even braille. Furthermore, any textbook written in PreTeXt and viewed in HTML format is fully accessible. In addition, these books are hosted on Runestone Academy, a Learning Engineering and Analytics Portal (LEAP).

Email: twj@judsonbooks.org