Mehretu, Julie. Notations, 2009. Ink and acrylic on canvas, 304.8 x 426.7 cm. Courtesy of the artist, The Project, New York, and carlier | gebauer, Berlin. © Julie Mehretu. Available at: http://www.guggenheim.org/new-york/exhibitions/past/exhibit/3156 (Accessed Sept. 10, 2013)
OAIster: union catalog of digital resources
MADID (Yale University Manuscripts & Archives Digital Images Database)
VIA (Harvard University Visual Information Access)
Bridgeman Art Library: art, culture & history images
Masters of Architecture Over 7,000 digital images of slides originally belonging to architects
Parker Library on the Web : Images of 6th-18th century manuscripts from Parker Library in Corpus Christi College, Camden.