Namaskaram !

We all know Vishnu Sahasranamam. There are others too. Narasimhar Sahasranamam, Ramar Sahasranamam, Anjaneya Sahasranamam etc.
We know very well that Bheesmsar recited Vishnu Sahasranamam. Kindly tell us on these sahasranamams.

1 Where from we got.
2. who recited them.
3. Are they equivalent to Vishnu Sahasrsnamam since other main avathars are that of Vishnu only.
4. What is the sanctity of being separate.

Also, please include some information on Lakshmi Sahasranamam and any other relevant things.

Yours sincerely,