An image for the unified model of AGN In a paper I'm writing, I've referenced an image I got from the NASA site at https://fermi.gsfc.nasa.gov/science/eteu/agn/ regarding the Unified Model of AGN. I captioned it

The AGN unified model, showing the BLR and NLR, as well as different types
based on the observational angle. Credit: Fermi and NASA: 
https://fermi.gsfc.nasa.gov/science/eteu/agn/


but my supervisor said that I should use proper referencing (I see that the image seems to be derived from this paper). The image from the NASA site is much clearer and easier to understand, and I'd much rather use it for clarity's sake.

What's the proper way to reference an image like this, which is derived from a paper?

Maybe I should just use the original image?

Or does anyone know of a better quality one from another paper, similar to the one from the NASA site?

EDIT: I should mention that this is a follow-up question to one I posted here.
I agree with your supervisor: If your paper is going to a peer-reviewed journal, you should cite peer-reviewed material. I also agree with you that the NASA version is clearer than the original figure, but if you're only going to refer to the image — i.e. not show a reproduction — I'm sure the reader can figure it out.

Alternatively, you could create your own (color) version with the annotations that are relevant for your work, and then write something like "…based on the schematic diagram of Urry &amp; Padovani (1995)".