GUDRO, Ilze; ZIGMUNDE, Alīda. Friedrich August Nauck (1855–1913) – Graduate of Riga Polytechnicum, Initiator of Control-Ticket Printing in Riga. History of Engineering Sciences and Institutions of Higher Education, Riga, Latvia, v. 4, p. 75–100, 2020. DOI: 10.7250/HESIHE.2020.005. Disponível em: https://hesihe-journals.rtu.lv/hesihe/article/view/HESIHE.2020.005.. Acesso em: 6 mar. 2026.