You can look in magic shop to see what one-time spells are there. But all summon spells are found in your magic book but you need magic skill to use. If you don't have the points to use them down load level 127 from this site.
I'm asking this because one of my followers is summoning an air elemental, but they don't have scrolls. And they don't know the spell of calling air elemental. :/
Well, Virgil has a Sword of Air that used to be mine... And the Magick Robes that used to be mine too... but nothing else... Could a shield summon an elemental? I don't remember its name but he has the shield that looks like an inverted teardrop.