APA Style

Einstein, :, A. (1916 (). Relativity: The Special and the General Theory (Reprint / Popular edition (depends on your copy). London / Princeton (: Routledge / Princeton University Press (choose based on your book).

MLA Style

Einstein, :, Albert. "Relativity: The Special and the General Theory". Reprint / Popular edition (depends on your copy London / Princeton (: Routledge / Princeton University Press (choose based on your book), 1916 (. PHD.