Tables in views

How can I find tables used in views ?
How can I find views used on tables ?

How can I know view text ?
I know the table "dba_views", but the column "text" is unexploitable.

Try DBA_DEPENDENCIES.

If you are interested in tables used in views:

SELECT *
FROM user_dependencies
WHERE type = 'VIEW'
AND referenced_type = 'TABLE';

It's OK
It's the result I was waiting for !