There has been this thing, this Dungeon Fantasy Kickstarter going around lately. You may have heard of it? Well Steve Jackson Games has been releasing supplements of Dungeon Fantasy for years and every volume has been excellent. The latest, Incantation Magic, was written by +Christopher R. Rice and Antoni Ten Monros. Chris writes the Ravens n' Pennies blog.
Dungeon Fantasy 19 Incantation Magic captures the essence for the Vancian magic system and allows you to use it within the GURPS system. Another optional magic system you can use in your game. Which I like personally. To give a different slant on magic from culture to culture.
Dungeon Fantasy 19 Incantation Magic is available in PDF for $7.99.