Annotation of Hans Bethe’s paper, Zeitschrift für Physik 76, 293 (1932), “Braking Formula for Electrons of Relativistic Speed”Christopher J. Fontes, Christopher J. Bostock and Klaus BartschatEur. Phys. J. H, 39 5 (2014) 517-536DOI: https://doi.org/10.1140/epjh/e2014-50027-1