Museums:
These museums offer many images of their collections online, but not all of them are available for reuse. Better for research than illustration.
Images in the Public Domain:
These images want to be used and you should most definitely do so, but please cite the source institution. Though many of the public domain images are long out of copyright, citing the source institution (that is, the museum/library/etc. wherein the original image/material is held) makes it easier for others to track down the originals of the images you use.
When using images in a paper, you must include a full citation of the image in your list of works cited.
MLA (Purdue OWL)
Lastname, Firstname. Work Title. Year of creation {if available}. Institution, City. Website. Medium. Date accessed {Day Month Year}.
Fairchild Aerial Surveys, Inc. Aerial View of Hoboken. N.d. New York Public Library, New York. New York Public Library Digital Gallery. Web. 24 January 2014.
APA (Landmark College)
Author (Role of Author). (Year image was created, if available). Title of work [Type of work]. Retrieved Month Day, Year, from: URL (address of website)
Fairchild Aerial Surveys, Inc (Photographer). (N.d.). Aerial view of Hoboken [Photograph]. Retrieved January 24, 2014, from: http://digitalgallery.nypl.org/nypldigital/id?1630052.
Chicago/Turabian (Colgate University) - requires institution, website, and item description.
Author, Title of work. Year of creation {if available}. Medium, description. Source, Location. From: Website, URL (access date Month Day, Year).
Fairchild Aerial Surveys, Inc., Aerial view of Hoboken. Not dated. Photograph, b&w, 18.5 x 24 cm. New York Public Library, New York. From: New York Public Library Digital Gallery, http://digitalgallery.nypl.org/nypldigital/id?1630052 (accessed January 24, 2014).
A Short Guide to Writing about Art by 
