One issue sometimes raised about Wikisource is how we know that we're working on the "right" books. Internet Archive is planning to textbooks starting from those which are most frequently assigned in USA schools: http://blog.archive.org/2017/03/29/books-donated-for-macarthur-foundation-10...
I was surprised to learn a project like OpenSyllabus exists and works, I emailed them to ask what it would take to do the same for other languages/geographies.
Nemo