Astronomy Without a Telescope, an interactive story book by George Jenner. DOS executable.
The IF Theory Reader, edited by Kevin Jackson-Mead and J. Robinson Wheeler.
Revised Kindle ebook edition of the IF Theory Reader. Contains all of the original content, plus an updated chapter by Graham Nelson, and an introduction by David Cornelson. Edited by Kevin Jackson-Mead and J. Robinson Wheeler, Kindle edition by J. Robinson Wheeler.
A chapter from "The ZX81 Pocket Book" by Trevor Toms (printed in 1981), describing an archaic text adventure authoring system, somewhat reminiscent of the one used by Scott Adams. "Authentic looking" HTML with GIFs. Scanned and converted by Vasyl Tsvirkunov.