iBooks warning and lesson for me

I opened iBooks and let it import my books from iTunes.

I had kept my books and pdfs in my own referenced folder system. They disappeared form that location, Documents/Books.

Fortunately I had cloned my drive before installing Mavericks, and had a back up book collection. Copied that to my main hard drive as Books_2.

Then I noticed as I went through the folders that some of my pdfs that were in my folders did not show in iBooks. I guess I had never imported those into iTunes in the first place.

I did a manual "add to library" of the missing items from the original Books and surprisingly the original was not touched. Have tested that again now for a number of pdfs.