Projects & Books

Hi
I am subscribed to Zoho Projects and have many ongoing projects. If I also subscribed to Books, can it be linked to a certain project ? IE; if I go that project, is there a direct link to the Books? or is it a totally different portal?

If I can link directly to the project (perhaps appear on my dashboard or menu bar) , does Zoho Books allow me to subscribe once and use in different individual projects? or I have to subscribe every time I want to link to a project?
Thanks
Lawrence