 A & C Black authorized the American firms of Charles Scribner's Sons of New York, Little, Brown and Company of Boston, and Samuel L. Hall of New York, to print, bind and distribute additional sets in the United States, and provided them with stereotype plates for text and graphics, specifications on the color and tanning quality of the leather bindings, etc., so the American-produced sets would be identical to the Edinburgh sets except for the title pages, and that they would be of the same high quality as the Edinburgh sets.Scribner's volumes and Hall volumes were often mixed together in sets by N.Y. distributors and sold this way as they were interchangeable, and such sets are still found this way.A total of 45,000 authorized sets were produced this way for the US market.