u/Glum-Mycologist-1112

I am looking for any book recommendations people have about the explanations for OCD. I don't want any kind of self help book or anything like that, just any books covering various explanations (for example: cognitive, psychodynamic etc.) for why OCD develops. I have already been studying the biological approach for explaining OCD and am interested in learning about others. Even free online resources that give real in depth explanations would be helpful, unfortunately everything I have found is lacking depth.

Thank you!