lower right in ink: Viterbo the 6th of April 1837 / as seen from the fornaci near Porta Faule, with / the spot of the tower of the beautiful Galliana. / LG
(C. G. Boerner, New York); purchased by NGA, 2008.
- C.G. Boerner. Neue Lagerliste 124. New York, 2008: no. 55.