The Perseus Project. http://www.perseus.tufts.edu/hopper/artifactBrowser?object=Vase&field=Collection&value=University+Museum%2C+University+of+Pennsylvania.
White, Donald J., Keith R. DeVries, David G. Romano, Irene B. Romano, and Yelena Stolyarik. The Ancient Greek World:The Rodney S. Young Gallery. Philadelphia: University of Pennsylvania Museum of Archaeology and Anthropology, 1995. See: p. 2
Bohen, Barbara. Die geometrischen Pyxiden. Kerameikos: Ergebnisse der Ausgrabungen. 13. Berlin: Walter de Gruyter, 1988. Page/Fig./Plate: 153 See: p. 67, no. 34 (number given as 30-40-1)