One of the collections here at Zetetic HQ is of what we like to call biblio-ephemera, or book related ephemera; including a half-hearted bookmark collection and quite a few bookplates, binders tickets, booksellers billheads and bookseller trade cards.
Our primary interest, however, are bookseller labels. Rickards in his excellent Encyclopaedia of Ephemera describes them as “in effect a miniature trade card … generally printed in black on a thin colour-tinted paper … and in a variety of shapes” (see below)
There are several books and websites devoted to collecting them, the best is www.sevenroads.org (then click on the link to the ‘Gallery of Book Trade Labels’), the site has hundreds of pictures of examples and also has a good bibliography on the subject, as well as several other web links