Which fantasy book series, with more than 80 million books sold in 37 languages, was written by Only You Can Save Mankind author Terry Pratchett?
Only You Can Save Mankind: Only You Can Save Mankind (1992) is the first novel in the Johnny Maxwell trilogy of children's books and fifth young adult novel by Terry Pratchett, author of the "Discworld" sequence of books. Discworld:  The series is popular, with more than 80 million books sold in 37 languages.
i don't know