It was a real old-school discovery when i first saw it, dating from 1979. It comes from "The Beholder" fanzine issue number three.
From Rpggeek we learn that
"The Beholder" was a long-running and popular UK fanzine published by Guy Duke and Michael Stoner, mainly focused on D&D and AD&D, and featured new monsters, magic items, character classes, and other game aids. Occasionally there were write ups of adventures. One regular feature was that there was a D&D/AD&D scenario with a map in every issue. Although there were no publication dates printed on the early editions of The Beholder, the first issues can be placed as being published in 1979 from references in other contemporary fanzines."The essay contained therein deals with an alternative magic system forAD&D. I am pleasantly surprised to see that it is founded on the concept of spell points.
Here it is for anyone to ponder.