Princeton University Press
The Princeton University Press published Albert Einstein’s four lectures at Princeton University in May 1921 as The Meaning of Relativity. The chapters of Einstein's book include “Space and Time,” “Special Relativity,” and “General Theory of Relativity.” In the chapter, "Special Relativity," Einstein writes:
We see that the energy, E, of a body at rest is equal to its mass. Had we chosen the second as our unit of time, we would have obtained
E = mc²
On March 27, 1972, the Princeton University Press and the Trustees of Albert Einstein made an agreement to publish The Writings of Albert Einstein. Helen Dukas, Einstein’s secretary from 1928 to 1955, catalogued Einstein's documents at the Institute for Advanced Study. They include writings to Mileva Maric, Marie Curie, and Elsa Einstein.