Einheitliche Feldtheorie un Hamiltonsches Prinzip.

Berlin: Verlag der Akademie der Wissenschaften in Kommision bei Walter de Gruyter U. Co, 1929. First separate edition. Fine. 6 pages in printed wraps.

Not exactly an "offprint," since the pages are numbered from 1, and the pamphlet is given its own title page, this is considered the first separate edition of a paper Einstein published in the periodical of the Prussian Academy. It is considered Einstein's initial effort, having established general and special relativity, to find a unified theory uniting gravity and electromagnetism, a problem he struggled with for his remaining life.