I I discovered Mary Thomas's Knitting Book in the library many years ago, and soon afterwards managed to find one in a second hand bookshop. It was the 1952 third impression of the original 1938 edition. It is in good condition but lacking its dust jacket.
The other week I found a copy of the original 1938 first edition, and I could not resist buying it. The cover has damp markings, but inside it is pristine. No marks, no sign of use. I don't think this copy would have had a dust jacket, because of the title on the front cover.
I thought I would sell the 1952 copy, but now I'm not so sure. It feels nicer to the touch, as it is printed on better quality paper and the binding is sleeker. So I expect I will keep both copies.
Mary Thomas covers all aspects of knitting. She has a nice style of writing and the book has lovely handdrawn illustrations, very clear and easy to follow. You really don't need any other knitting book! (Things have of course changed in the last 70 years and there is no top down knitting or decimal needle sizes.) I ought to read it through again.