2¼ pages, 8vo, 223 x 140 mm. (9 x 5½ in.), page 1 incorporating two carefully labeled geometrical diagrams." /> EINSTEIN, ALBERT. Autograph letter signed ("Papa") to Hans Albert Einstein, n.p. [Berlin], 9 December 1917. <I>2¼ pages, 8vo, 223 x 140 mm. (9 x 5½ in.), page 1 incorporating two carefully labeled geometrical diagrams</I>. | Christie's