 Über die Konstitution des Elektrons by Walter Kaufmann (1906)

Annalen der Physik 324(3), 487–553; doi:10.1002/andp.19063240303. Reproduced original German text; introductory discussion and electric/magnetic deflection analysis. Distinct from the shorter 1905 paper of the same title. Historical model comparisons are not presented as modern confirmation of his preferred model.