Holly Black and Tony DiTerlizzi
These are the books by Holly Black and Tony DiTerlizzi that are reviewed on this site:
The Spiderwick Chronicles: The Seeing Stone
Arthur Spiderwick's Field Guide to the Fantastical World Around You is a problem for Jared Grace when he finds it in his uncle's study. There are plenty of creatures out there that don't want Jared to read it. But the Guide is also the best help Jared could have in his battle with the creatures...