Vintage Faux Fur Reversible Coat

I have been unable to identify the brand name of this amazing and seemingly one of a kind coat. The only identifying mark is a GS on the back of the green side. There are 2 side pockets on both the fur side and the green side. It appears the green side is perfect and the only wear is fading on the buttons on the fur side. I wear a medium and it’s a little big. I am 5’6” and it hits me mid shin. It’s a heavy and beautiful coat for all you cold climate shoppers!