all clinicians:
SELECT r.*
FROM referrer r
JOIN referrer_posting rp
ON r.id = rp.referrer_id
JOIN hospital h
ON h.location_id = rp.location_id
WHERE h.region_code = 'RR8'
SELECT r.*
FROM referrer r
JOIN clinician_region cr
ON cr.referrer_id = r.id
WHERE
cr.region_code = 'RR8'