PPT Slide
Then in a footnote on page 566 Planck writes, "Einstein has already drawn essentially the same conclusion by application of the relativity principle to a special radiation process, however under the assumption permissible only as a first approximation, that the total energy is composed additively of its kinetic energy and its energy referred to a system with which it is at rest.” I consider Einstein's statement of E = Mc2 as invalid since he had mixed two distinct observations without his required relativistic alterations to even arrive at what was but an approximation. Assuming that Poincaré's results are considered as incomplete, then the first complete derivation for one frame of reference and for a specific form of radiation was given by Planck as based upon Poincaré's work.