Graphic representation of the periodic table of chemical elements designed as an unsymmetrical series table in which the elements of short periods are placed in subgroup "a." This table was originated by German chemists Karl Arnold (1853-1929) in 1885 and classified by chemist Edward G. Mazurs as Type IC2-5 in his seminal work Types of Graphic Representation of the Periodic System of Chemical Elements (1957). This illustration appears as Figure 33 on page 111 of Mazurs' 1957 publication.
Mazurs, Edward G., and Karl Arnold. “Unsymmetrical Series Table with Elements of Short Periods Placed in Subgroup ‘a.’” Glass, circa 1885–1957. Edward G. Mazurs Collection of Periodic Systems Images, Box 1. Science History Institute. Philadelphia. https://digital.sciencehistory.org/works/xk81jm00j.