Old woman

This is a portrait I did a while ago for school. 

I have searched EVERYWHERE (litteraly) for the reference photograph I used and wasn't able to find it.
I think I have already watched every portraits of old women on the internet, but if you do find it, or have already seen it, I would really like to know it and be able to credit the photographer. Thanks a lot. 

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I don't have a better picture to show you since the original drawing is in my parents' house, but I think I will try to do a better shot on my next visit.