Cita APA (7th ed.)
Einstein, A. The Collected Papers of Albert Einstein: The Berlin Years : Writings, 1918-1921. Princeton University.
Cita Chicago (17th ed.)
Einstein, Albert. The Collected Papers of Albert Einstein: The Berlin Years : Writings, 1918-1921. Princeton, EUA: Princeton University.
Cita MLA (9th ed.)
Einstein, Albert. The Collected Papers of Albert Einstein: The Berlin Years : Writings, 1918-1921. Princeton University.
Atenció: Aquestes cites poden no estar 100% correctes.