Seconding "Starting Forth" and "Thinking Forth". After that, Jonesforth (https://rwmj.wordpress.com/2010/08/07/jonesforth-git-repository/ https://rwmj.wordpres

Seconding "Starting Forth" and "Thinking Forth". After that, Jonesforth (https://rwmj.wordpress.com/2010/08/07/jonesforth-git-repository/ https://rwmj.wordpress.com/2010/08/07/jonesforth-git-reposit...) is an excellent example of Literal Programming that starts with an Assembly listing and bootstraps into a complete usable Forth system. No better way to learn Forth than to actually implement one...