Consideraţii privind stampilele Legiunii XIII Gemina de la Ulpia Traiana Sarmizegetusa. Considerations on tegular materials of the Leg. XIII. Gemina in Ulpia Traiana Sarmizegetusa - Bădău-Wittenberger, Mihai (Acta Musei Napocensis, 24/25 (1987/88), 1987)