The other was Enchantress from the Stars by Sylvia Engdahl. In 2002 I tracked down a first edition, ex-library copy (remarkably pristine) and bought it. This weekend I was thinking about the girl who blogged that Shock Point was her favorite book of all time. Which made me think of my two favorite books. On Amazon, I was shocked to see a post by Ms. Engdahl. She was alive! And she lived 90 minutes away. I promptly emailed her. I got an email back. It sounds like her physical health is not the best, but she is still the same sharp woman who was a pioneering female computer programmer. Her books transported me - I don't think she can imagine how much they meant.
I hope in my career I give one person that level of joy.