If you'd like to see what Donn's BASIC was like, you can! The Internet Archive has a version that runs in-browser [1].
Although the Folklore article says there were two books describing Donn's BASIC, I believe there were at least three: Introduction to Macintosh BASIC, Using Macintosh BASIC, and The Macintosh BASIC Handbook. All three are available at vintageapple.org [2].