Sparky's Productivity Book

In the most recent episodes about the 2025 Productivity Field Guide, David mentioned multiple times that he has also written a book about productivity. I’d like to check it out - where can one find it?

Was he talking about an old book? If not, the current Productivity Field Guide has an ebook that goes with it - it’s a big PDF. 141 pages.

Thank you - that was not clear to me after listening to the episode. I somehow walked away assuming that the book is a separate purchase. Good to know.