The Puranas include myths of creation and cosmology, in addition to the deeds of the great gods. Examples include the Bhagavata Purana and the Vishnu Purana, centering on the god Vishnu; the Shiva, Skanda, and Linga Purana about Shiva; the Brahma Purana about Brahma; and the Brahma Vaivarta Purana, which tells myths of Devi and of Krishna and the popular elephant-headed god, Ganesha. Gurus, and other sages and priests, use the Puranas to popularize the complex concepts of Hinduism by way of stories of the gods. Along with the Rigveda and the epics, the Puranas are the richest source of Hindu mythology.