How to combine direct and indirect responsibility Query

Dear Expert,

May I know how can I combine both direct and indirect responsibilities query. I manage to get the direct resp but unable to include indirect resp to get detail extraction

Below is my query

SELECT

a.user_id,

a.user_name,

a.description "NAME",

a.email_address,

b.responsibility_id,

c.responsibility_name,

c.description "RESPONSIBILITY DESCRIPTION",

b.start_date,b.end_date,b.creation_date, b.last_update_date,a.last_logon_date

FROM

apps.FND_USER a,

apps.FND_USER_RESP_GROUPS_DIRECT b,

apps.FND_RESPONSIBILITY_VL c

WHERE c.responsibility_id = b.responsibility_id