van Dongen, Jeroen Department Structural Changes in Systems of Knowledge, Max Planck Institute for the History of Science, Max Planck Society;
van Dongen, J. (2004). Einstein's methodology, semivectors and the unification of electrons and protons. Archive for History of Exact Sciences, 58(3), 219-254. doi:10.1007/s00407-003-0074-1.