Foundation Trilogy (omnibus) (1981) by Isaac Asimov
1. Prelude to Foundation (1988) by Isaac Asimov
2. Forward the Foundation (1993) by Isaac Asimov
3. Foundation (1951) by Isaac Asimov
4. Foundation and Empire (1952) by Isaac Asimov
     aka The Man Who Upset the Universe
5. Second Foundation (1953) by Isaac Asimov
6. Foundation's Edge (1982) by Isaac Asimov
7. Foundation and Earth (1986) by Isaac Asimov

1. Foundation's Fear (1997) by Gregory Benford
2. Foundation and Chaos (1998) by Greg Bear
3. Foundation's Triumph (1999) by David Brin