
For the valued reader in your circle, you could order the trade paperback editions. For the truly discerning, hardcovers may be the best choice.
In the old days, I used to sell autographed copies myself by mail. But that was before all the states got compulsive about collecting sales tax, and it became unworkable. So, if you’d like your copies autographed, the best way is to bring them to a con and ask me to sign them in person. That’s so much nicer, anyway.

The Reefs of Time — paperback | hardcover
Crucible of Time — paperback | hardcover
Your gift recipients will thank you, and so will I.
P.S. If you’d rather give other print volumes in the series, here are some other options:
Neptune Crossing | Strange Attractors | The Infinite Sea