The self-teaching guide is impressive. The programmed instruction format is a great way to learn, and it works both in print and online. I wish there were entire curricula available this way.
Edit: It seems that Wiley has published a number of books in the self-teaching guide series:
Don Inman, Ramon Zamora, Bob Albrecht.
TRS-80: https://www.amazon.com/Advanced-TRS-80-Level-II-BASIC/dp/047...
TI-99/4a: https://www.amazon.com/Introduction-TI-BASIC-TI-99-4A/dp/081...
Visual basic for dos: https://www.amazon.com/Visual-MS-DOS-Prentice-Innovative-Tec...
VIC-20: https://www.amazon.com/Vic-BASIC-User-Friendly-Guide/dp/0835...
Here is the full TRS-80 text: https://archive.org/details/trs-80-level-ii-basic-a-self-tea...
Who were these guys? They were all over the map.