Levi-Civita, Tullio, 1873-1941.
A simplified presentation of Einstein's unified field equations / by Tullio Levi-Civita ; authorized translation by John Dougall.
Einstein, Albert, 1879-1955. Zur enheitlichen feldtheorie.
Gravitation
Electromagnetism.
1929.
Dougall, John, b. 1867.