How do I find table Locks?

[elintrend]

select a.object_id,a.object_name,b.sid,b.serial#,b.username,
c.os_user_name,c.locked_mode
from v$session b, v$locked_object c , dba_objects a
where a.object_id=c.object_id and
b.sid=c.session_id;