Let's say you have used information from this book and need to cite it. Here is the catalog record for it:

gurdjieff book record

APA tells you to include:

Author's last name, first and middle initials (if available). (Year of publication). Title of work: Capital letter also for subtitle. Location: Publisher.

 

So you write:

Wellbeloved, S. (2003). Gurdjieff: The key concepts. New York: Routledge.