How to limit this query to only those authors that wrote more than one book using Oracle?

How to limit this query to only those authors that wrote more than one
book using Oracle?

I have been trying to limit this query to just the authors that wrote more
than one book (should be four), but I can not figure it out. Can someone
please help?
Here is my code:
SELECT title, COUNT(authorid) AS "Number of Authors"
FROM book_author, books, publisher
WHERE publisher.pubid(+) = books.pubid
AND books.bookid(+) = book_author.bookid
GROUP BY title;
Here are the results:
SQL> SELECT title, COUNT(authorid) AS "Number of Authors"
2 FROM book_author, books, publisher
3 WHERE publisher.pubid(+) = books.pubid
4 AND books.bookid(+) = book_author.bookid
5 GROUP BY title;
TITLE Number of Authors
------------------------------ -----------------
DATABASE IMPLEMENTATION 3
PAINLESS CHILD-REARING 3
HOW TO GET FASTER PIZZA 1
SHORTEST POEMS 1
BIG BEAR AND LITTLE DOVE 1
BODYBUILD IN 10 MINUTES A DAY 2
HOLY GRAIL OF ORACLE 1
HANDCRANKED COMPUTERS 2
HOW TO MANAGE THE MANAGER 1
COOKING WITH MUSHROOMS 1
BUILDING A CAR WITH TOOTHPICKS 1
E-BUSINESS THE EASY WAY 1
REVENGE OF MICKEY 1
THE WOK WAY TO COOK 1
14 rows selected.
Any help would be much appreciated.