EINSTEIN, ALBERT. Die Grundlage der allgemeinen Relativittstheorie. Leipzig: Johann Ambrosius Barth, 1916. 8vo, original printed wrappers, defective; title detached. First separate printing. Offprint from Annalen der Physik, Volume 49, no. 7. Weil 80a -- Bemerkung zu dem Gesetz von Etvs. Leipzig: Barth, 1911. 8vo, original printed wrappers, lower portion of lower cover clipped, affecting text. First separate printing. Offprint from Annalen der Physik, Volume 34. Weil 38. (2)