In addition, Brugmann stayed in touch closely with the scholars who were revolutionizing Indo-European linguistics for the daughter languages, in particular Bartholomae for Old Iranian, Hübschmann for Armenian, and Rudolf Thurneysen for Old Irish.
Asemade, Brugmann estaba en contacto cos estudosos que estaban a revolucionar a lingüística indoeuropea nas linguas fillas, en particular con Christian Bartholomae para o iranio antigo, Johann Heinrich Hübschmann para o armenio e Rudolf Thurneysen para o irlandés antigo.