I think this may not just be American Sign Language, but is hopefully useful. This text is in use at Western Oregon University. It can be freely accessed, shared under similar licensing, downloaded, and modified. It is available in a variety of file types at the link below this paragraph. Additionally, it is available in the Open Textbook Library, where it has also undergone peer review. Click here to read those reviews.
Exploring Open by Kathy Essmiller is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.