sentences:  Working into early 1926, Eckart developed the formalism.When Erwin Schrödinger’s first paper in the series of four on the wave mechanics formulation of quantum mechanics was published in January, Eckart soon realized that the matrix formulation and wave formulation of quantum mechanics were equivalent; he submitted his paper to the "Proceedings of the National Academy of Sciences of the United States of America" for publication.However, it was communicated on May 31, 1926, and Schrödinger’s paper on the equivalence was received on March 18, 1926, thus giving him credit for the realization.