Andre Norton was one of my first favorite S.F. authors. I think the first story of hers that I read as "The Zero Stone", published in 1968, which was just about the time I was really getting into Science Fiction. Somehow, I never caught on to the fact that "Andre" was supposed to be a man's name (to make it easier for her to publish in the man's genere of Science Fiction), I was aware from the beginning of her feminine voice.

Her Witch World series were had begun a bit earlier than that, and were not likely to be found in Elementary School libraries, so I didn't come upon them until later, and I never really got caught up in them. Ms. Norton was a prolific writer, and finding the books of a series that had not been explicitly published as a trilogy was difficult even then, especially trying to find them in order, so I never really got caught up in the saga.