Almost every 10 inch Mercury lp I have. Only one of the Maas covers is signed, the rest are guesses based on style. Jan August was a fine cocktail piano player, I keep these with records I play. The rest are fun covers. I love the early embossed ones, I assume some of them are Maas also.
Collecting Record Covers 
I agree those are likely by Maas. He certainly shows a Steinweiss influence in these covers.
The early embossed Mercury releases are almost definitely George Maas. At least that’s what my research thus far has indicated. I love those covers, too.