6 2 8 D O C . 4 1 4 C A L C U L A T I O N S
AD. [28 025]. Written on the same page as the preceding document, on the verso of [28 026].
Dated by the fact that it is written on the same page as the preceding document.
Einstein starts from De Broglie’s relation between mass and wavelength of material particles
(see Einstein 1925f [Doc. 385], eq. ).