[TYPO3-mvc] two objects, I see only one

[mario chiari]

Hello

My first post to the list. 
I am trying to learn a little of extbase+fluid.
I am using the Ext Builder, and I define something as it follows:

Object: Book (entity); Properties: Title and Comment; relation: Author
1:1 to Author;
Object: Author  (entity); Properties: Name and Comment; relation Book
1:1 to Book.

Thanks to Ext Builder, I am able to list Books in the FE, each with its
title, comment, author.name, and author.comment.

So far so good. Now, I miss to see:

-- which piece of code is such that Book object is rendered, instead of
the Author one;
-- a way to configure the plugin as to render either one of the two
objects, or even both;
-- a way to configure the BE form as to select the author of a new book
from the records of the Author table (is this just a TCA issue?)

I hope I explained myself
thanks
mario


ps I am looking at 
http://flow3.typo3.org/documentation/manuals/fluid/fluid.usermanual/
is there any other intro?