How do you find the "unmatched" fields in a join

In this example (from the Oracle documentation):

SELECT ename, job, dname
FROM emp, dept
WHERE emp.deptno (+) = dept.deptno;

How would I get the list of departments with no employees?

i.e.

AND emp.deptno is null? Received on Fri Jun 08 2001 - 16:33:24 CEST