If you are in Holland, you might enjoy the review of The Art of American Book Covers 1875-1930 in Boeken over Boeken (Books about Books). If you are near Den Haag, the Koninklijke Bibliotheek has the three Limited Edition volumes the reviewer describes as "Van de boeken die hij daarvoor heeft verzameld heeft hij drie catalogi gemaakt in gelimiteerde edities, die nogal kostbaar zijn." If you are elsewhere and your local bookstore does not have a copy of The Art of American Book Covers, amazon.com offers a substantial discount.
Meanwhile, you may have noticed that I have not been updating this blog recently. Don't worry, in the future it will become much more active. I have been busy getting out Volume 3 of American Decorated Publishers' Bindings 1872-1929. It has 300 designs that were not in the first two volumes, bringing the total to 1,100 cataloged designs + variants. The cover features an adaptation of a Thomas Watson Ball design from 1899: