Puranas.

There are 18 Puranas. they fall into three groups.
The first set of six puranas are authoritative, sacred these are called Sattvika Puranas. 
Vishnu Purana
Bhagavatam
Narada Purana
Padma Purana
Varaha Purana
Garuda Purana.
The second set of six puranas are of medium quality i.e. the whole thing cannot be accepted as true. These are called Rajasa Puranas.
Vamana Purana
Brahma Purana
Markandeya Purana
Bhavishya Purana
Brahmanda Purana
Brahma Vaivarta Purana
The third set of six Puranas cannot be taken as perfectly valid. only some portions of them which are not opposed to vedas, can be taken as authoritative. these are called Tamasa Puranas.
Matsya Purana
Kurma Purana
Agni Purana
Linga Purana
Siva Purana
Skanda Purana.
Vedas are the ultimate authority. so the Puranas which contradict the vedas cannot be taken as authority.