Ursus specializes in illustrated books from the fifteenth century to the present. While most people might think of prints as free-standing objects, the fact remains that, since the beginnings of the printed book, artists have collaborated with authors to produce unique works of art. Nowhere is this more apparent than in the twentieth century where there are numerous examples of dealers or publishers harnessing the talents of authors and artists, from Kahnweiler and Vollard to The Petersburg and  Arion Presses.

The advantage these books have over single prints is they are often able to throw a unique light on the cultural zeitgeist of the moment. For example no understanding of Cubism would be complete without an examination of the books produced by Kahnweiler, and the understanding of major art movements such as Futurism in Italy and Constructivism in Russia are partially dependent on their illustrated books being taken into account.