Article in: Journal für die reine und angewandte Mathematik. 77th Band. Pp 258-262. 10½x7½, modern half-calf, spine gilt. First Printing, Journal Issue.

First appearance of Cantor's theory of transfinite numbers, a cardinal or ordinal number designating the magnitude of an infinite set--this being the first demonstration that there are different orders of infinity and the basis for modern set theory and analysis. One of the most important single papers in the history of mathematics. Very rare; no copies appear at auction in the last 25 years.