I'm looking for vendors (or locations) of conjuration spell books. Specifically I'm looking for summon flame atronarch. However I can't find the conjuration trainer in the mage college. (I'm only a couple quests in to that questline if he appears later).
Most villages have a court wizard alongside the Jarl, otherwise you could go to the College in Winterhold, which has everything you need. Keep in mind that as long as you don't have a high enough skill, they won't sell it to you.