After his graduation from Kunstgewerbeschule, Herdeg went on to continue his studies in 1928 under the guidance of Otto Hermann Werner Hadank (O.H.W Hadank), a leading figure in German package design.Two years later, Hadank would extend to Herdeg the same hospitality as Keller did, by employing him as a calligrapher, package and logo designer.
Otto von Bismarck | Hermann Göring | Werner Herzog | Hermann Hesse | Hans Werner Henze | Otto | Werner Heisenberg | Otto III | Rainer Werner Fassbinder | Otto Piene | Otto I, Holy Roman Emperor | Otto I | Hermann von Helmholtz | Otto Preminger | Hermann Nitsch | Otto II | Otto Dix | Otto Natzler | Otto II, Holy Roman Emperor | Otto Binder | Hermann Hauser | Hermann Bondi | Werner | Otto Skorzeny | Otto Schenk | Otto of Brunswick | Otto Kerner, Jr. | Hermann Zapf | Otto Steinbrinck | Otto Kerner |