is out of print, as is _Concise survey of computer methods_ and rather pricey.
Oddly, _Knowing and the Mystique of Logic and Rules_ (which has an even lengthier title after a colon...) has four entries at Goodreads and is listed under "P. Naur" and is even pricier, quite expensive on Amazon:
It was reprinted elsewhere, in an agile book (which one?) which this (more readable than linked) copy [1] is from. I think the other one might be from another edition of the same book. I ordered Computing A Human Activity a few weeks ago, its still in shipping, probably got the cheapest remaining copy.
[1] https://pablo.rauzy.name/dev/naur1985programming.pdf