Philo as a Kabbalist??

Surfing around, a certain webpage gave me a brief hint into a world I did not known Philo were introduced into, but a book was published in 2001 that tries to introduce Philo as a kabbalist. It was published in Dutch, but now there seem to be an english version out too: H.J. Spierenburg, de kabbala van Philo van Alexandrie. Hardcover pp. 167 Pagina's | Uitgeverij Ankh-Hermes | 2001
ISBN: 9020285580.
Henk Spierenburg, THE PHILONIC SECRET TEACHINGS.The Kabbalah of Philo of Alexandria. LOGOS SERIES Hardback 200 pages NLG 39,50 ISBN 90 202 8558 0. The page which at first demonstrated the existence of this book provided the brief comments to be found here.

However, as both these seem to have the same ISBN number, they can hardly represent different issues. I'm confused.
The whole case seem to me to be somewhat esoteric. If anyone 'out there' knows anything about this book, please use the comment field below for further information.