The 39 Clues books were also co-written by various authors, including:
* Peter Lerangis
* Gordon Korman
* Patrick Carman
* Linda Sue Park
* Roland Smith
* Jude Watson (this is where the confusion might come in, but she co-authored books in the series, not the whole thing)
Jude Watson is a different author, known for her books in the "Star Wars" series, like "Jedi Academy" and "Jedi Apprentice."
Hopefully, this clears up the confusion!