Christopher Stasheff books for sale - use the search engine right, type in Stasheff in the author section.
Christopher Stasheff (born 1944) is an American science fiction author and fantasy author whose novels include The Warlock in Spite of Himself (1969) and Her Majesty's Wizard (1986). He has a PhD. in theatre and teaches radio and television courses at Eastern New Mexico University in Portales, New Mexico.
Stasheff's stories could be categorized as "medieval fantasy"; they are filled with sorcery, monsters, castles, etc. Stasheff has written several series of novels featuring a wizard or warlock as the main character. However, in at least the Warlock series, the "fantasy" is actually psionic or esper powers: telepathy, telekinesis, teleportation, psychometry, etc., with time-travelling enemies, and the protagonist's best friend is a high-tech computer AI in a robotic equine body.