I heard, years later, that the "trilogy" was expanding.
I decided recently to read the full series. I was amazed to discover that the series now consists of 7 books.
When looking into the best order in which to read the "trilogy", I discovered that opinions differ. But all agree that more than 7 books are involved!
Follow this link to find some conflicting opinions/advice.
Asimov himself set out (in "Prelude to Foundation") an order in which the books should be read. But then he went on to add "Forward the Foundation" to the series!
So the order I am going to use is neither the order in which they were published nor the order recommended by Asimov himself. Instead it is the one set out by a user named "Ojisan642" at the link above. It is:
- I, Robot
- The Elijah Baley series
- The Caves of Steel
- The Naked Sun
- The Robots of Dawn
- Robots and Empire
- The Galactic Empire trilogy
- The Currents of Space
- The Stars, Like Dust
- Pebble in the Sky
- The original Foundation Trilogy:
- Foundation
- Foundation and Empire
- Second Foundation
- Foundation's Edge
- Foundation and Earth
- Prelude to Foundation
- Forward the Foundation
So 15 novels in all! I just completed the fourth book this morning. Enjoying them very much so far.
And if I want to read more after that, he claims (at the end of the fourth book) to have "published over 260 books."
And WikiPedia goes further to claim that he has "written or edited more than 500 books."
What an unbelievable achievement!