Adding Custom Fields linked to Custom Post Type

Hi,
I’m massively using Types on a website I’m working on since it’s really easy and powerfull.
I have 2 Custom Posst, let’s call them “Book” and “Authors” .

In the edit panel for a Book, I would like to add a custom field “Author” wich would be a dropdownlist with the author associated to the book.

I’m wondering how to achieve this, ie the dropdown list should retrieve all Authors, show them and store (for ex) the ID of the selected author.

Of course, this is an example, the project is a bit more complex (so that I can’t use taxonomy “author”, or use the parent relations built in types).

Is ther a way to acheive this (without the use of Views, indeed)

Thanks in advance.

https://wordpress.org/plugins/types/