C. Schuler: Portrait of German engraver Christian Haldenwang (1770-1831), dated 1827, inscription: "Abb. 4. J. Christian Haldenwang. C. Schuler ad naturam del. et sculp 1827 (Karlsruhe, G[eneral]-L[andes]-Archiv)."
C. Schuler ad naturam del. et sculp 1827
own scan