How to query a list of posts titles into the choices for Advanced Custom Fields (Wordpress)?

I have two custom post types in WordPress: Authors and Books. I want to use Advanced Custom Fields to add a checkbox list when I add a new Book. This checkbox list contains the entire list of authors.

My purpose is to create a dynamic list of items (authors) to tick away when creating a new Book, as new authors will be added from time to time. For simplicity, let's focus on Authors' titles.

This image will make things clearer:

Is there any known way to do it?