Oscar Reutersvärd (1915 Stockholm, Sweden-February 2, 2002), "the father of the impossible figure", was an artist who pioneered the art of impossible objects. These are objects such as what was later renamed the Penrose triangle, which appear solid on the page, but cannot be built. This triangle, first created in 1934, was honored in 1982 on a Swedish stamp. In comparing his work to that of the much more famous artist of the impossible, M. C. Escher, it can be observed that Escher builds inhabited worlds around impossible objects, whereas Reutersvärd's designs generally consist of pure geometric forms. Reutersvärd produced more than 2500 figures all in isometric projection. There have been numerous books published on his works in Swedish, English, Polish, and Russian.