John Spencer's Mini-Manual on Urban Defense

John Spencer is a veteran and author who has written a "mini manual" on urban defense. He says he mainly wrote it for the Ukrainians. There is a free PDF available for download from his site:

https://www.johnspenceronline.com/mi...-urbandefender

As much as I enjoy guns and shooting, I know very little about combat tactics. I'm curious to hear from those who have experience with this sort of thing if this is good info or just academic theory.

EDIT: Fixed link