The six Vaishnava-Purānas are: Vishnu-, Bhagavata-, Padma-, Nārada-, Garuda-, and Varāha-Purāna.
Source: The Encyclopedia of Eastern Philosophy and Religion: Buddhism, Hinduism, Taoism, Zen. Shambhala Publications, Inc.
Documents on the Vaishnava-Purānas
Books on the Vaishnava-Purānas
External links: Puranas / Mahapuranas
Padma-Purana / Vishnu-Purana / Bhagavata-Purana / Narada-Purana / Varaha-Purana / Garuda-Purana