In “The Room Where It Happened: A White House Memoir,” Bolton will go beyond Ukraine, and argue there was “Trump misconduct with other countries,” the source said…

Behind the scenes: People close to Trump have been worried about the book because Bolton was known as the most prolific note taker in high-level meetings, Jonathan Swan reports.

Bolton would sit there, filling yellow legal pad after yellow legal pad with notes.

In short: Bolton saw a lot, and he wrote it down in real time. And when he left, the White House never got those notes back.