An open-access linear algebra textbook authored in PreTeXt.
See HTML output of the two-semester version at
https://sites.ualberta.ca/~jsylvest/books/DLA/
and of the one-semester version at
https://sites.ualberta.ca/~jsylvest/books/DLA1/
Note that current work is focused on usable HTML output --- no serious effort has yet been made to ensure usable LaTeX output.