There are said to be eight forms of Devi Lakshmi, called as Ashta Lakshmi ( अष्ट - लक्ष्मी ) .
Which all scriptures give details about them?
I'd like to further know, if they are to be considered as a parallel to the Vyūha manifestations of Lord Vishnu or just normal incarnation manifestations like the Nava-Durgas or the Dasha-Avataras ?
How does, and which scriptures define their origin, significance and mode of worship?
Please try to include (if possible), all the scriptures which might give details about the Ashta-Lakshmi concept.