Instpubs, SQL, filter Publisher

SELECT
    authors.au_fname AS FirstName, authors.au_lname AS LastName,
    COUNT(DISTINCT publishers.pub_id) AS Publishers
FROM authors
    INNER JOIN titleauthor
        ON dbo.authors.au_id = titleauthor.au_id
    INNER JOIN titles
        ON titleauthor.title_id = titles.title_id
    INNER JOIN publishers
        ON titles.pub_id = publishers.pub_id
GROUP BY authors.au_fname, authors.au_lname
HAVING COUNT(DISTINCT publishers.pub_id) = 2