Original edition by Albert Einstein

Rare unsigned booklet: Zur Einheitlichen Feldtheorie [On the Unified Field Theory]. The first edition of one of Einstein's last important scientific works. Berlin: Walter de Gruyter, 1929. Original orange printed wrappers, 7.25 x 10.25, 8 pages. In very good to fine condition with minor wear and toning to covers. By 1929, Einstein had solved the major problems he encountered in writing the field equations for his unified field theory; this "unified field" theory would be a generalization of his theory of gravity, including all electromagnetic phenomena. (C 222)