The Physical Principles of the Quantum Theory (German: Physikalischen Prinzipien der Quantentheorie publisher: S. Hirzel Verlag, 1930) by Nobel laureate (1932) Werner Heisenberg and subsequently translated by Carl Eckart and Frank C. Hoyt. The book was first published in 1930 by University of Chicago Press. Then in 1949, according to its copyright page, Dover Publications reprinted the "unabridged and unaltered" 1930's version.

Frank Clark Hoyt was an American physicist, regarded as one of the first theoretical physicists to come from the USA in the period that quantum mechanics was being developed.