UNION ALL query using WITH statement breaks

I wrote a query using with statement and union all. But, I am not used to writing complex queries. It keeps breaking in the union all. Please point me where it is wrong?

WITH t1 (source, target) AS (
SELECT 
t1.study_name,
t1.site_id

FROM  iv_p_mv


UNION ALL


SELECT 
t2.study_name,
t2.site_id
FROM  iv_p_mv as t2 left outer join t1 on t1.study_name = t2.study_name

)

SELECT 
study_name,
site_id
FROM  t1 

Error:

Reference t1 is not found.

Answer

Just out of curiosity. Is this what you need?

WITH source AS (
    SELECT t1.study_name, t1.site_id 
    FROM iv_p_mv t1),
    target as (
    SELECT t2.study_name, t2.site_id
    FROM iv_p_mv t2 LEFT OUTER JOIN source s ON s.study_name = t2.study_name
    union all 
    SELECT s.study_name, s.site_id
    FROM source s)   
SELECT
    study_name,
    site_id
FROM target;

@KSp *I can see that you accepted this aswer, but if you want a recursive query, it should look more like (see answer and comments from @mathguy)

WITH t1 (source, target) AS (
    SELECT study_name   source,
           site_id      target
    FROM iv_p_mv
    UNION ALL
    SELECT t2.study_name,
           t2.site_id
    FROM iv_p_mv t2, t1
    WHERE t1.source = t2.study_name (+)
)
SELECT source, target FROM t1