saving data of some other model

I have two models.
Books
Authos

books... has_many :authors

now you can add author through authors controller after selecting a
book.

but I also want to be able to add author through book's new/edit form.
like there is a field in which I can provide authors names so that those
would be stored in authors table with this book_id.

I am not really sure how to do this while I am using book controller.