select book_id from authors
where
  author_name in ('Smith','Jones')
group by book_id
having count(*)=2
except
select book_id from authors
where
  author_name not in ('Smith','Jones');

##</code><code>##

select book_id from authors
where
  author_name in ('Smith','Jones')
  and book_id not in (
    select book_id from authors
    where
       author_name not in ('Smith','Jones')
  )
group by book_id
having count(*)=2