This is a list of all recommended characters that are different verisons of Book.
Dictionary was in Episode 16 and Episode 17. She is a dictionary with no limbs. She was recommended by jmarston123, Inlumino, MrGeorge and thecartoonremix4.
Emerald Book appeared in BFB 2. She is a book made out of emerald.
Evil Book is a recommended character in Insectophobe's Nightmare 3. She was recommended by Redking632. She placed 12th out of the Top 25 recommended characters. Unlike Book and the other evil variations, her cover colors are both purple and red. Her friend is possibly Book, the character she was based off.
Pandora Book was in BFB 4.
Science Book was in Today's Very Special Episode, Four Goes Too Far, The Liar Ball You Don't Want and This Episode Is About Basketball.