How To find Oracle API's for any module?

How To find Oracle API's for any module?

select substr(a.OWNER,1,20)
, substr(a.NAME,1,30)
, substr(a.TYPE,1,20)
, substr(u.status,1,10) Stat
, u.last_ddl_time
, substr(text,1,80) Description
from dba_source a, dba_objects u
WHERE 2=2
and u.object_name = a.name
and a.text like '%Header%'
and a.type = u.object_type
and a.name like 'AR_%API%' –- Check for AR Related APIs
order by
a.owner, a.name;