There are 3 tables books, m2m_books_authors(for communication many-to-many), authors.
In the books there is a field b_id, b_name.
In m2m_books_authors fields b_id, a_id.
Authors in the fields a_id, a_name.
I'm doing a query with a join:
SELECT b_name, a_name from books join m2m_books_authors using(b_id) join authors using(a_id)
What to add to have chosen only those books with more than 1 author?