ΕπικεφαλίδαHagen, August Matthias χρησιμοποιείται σε: Integrated Authority File (GND), Germany
Πηγές
Βρίσκεται σεDbA. — Thieme-Becker. — BBLD: Stand: 21.02.2020: https://bbld.de/000000037140737X
Hagen-Schwarz, Julie. Portrait of Artist August Hagen. Tartu Art Museum [Julie Wilhelmine Hagen-Schwarz / Tartu Art Museum -- Public domain -- http://commons.wikimedia.org/wiki/File:Hagen-Schwarz, Julie. Kunstnik August Hageni portree.jpg]