Fair use considerations:

"There are no known restrictions on these photographs. However..."
American Memory: Photographs, Prints, and Drawings, Library of Congress--Civil War Photographs, 1861-1865-- Restrictions on Selected...

"Yes, you may link to any of my pages (and thank you), but DO NOT link directly to an image."
Carol Gerten's Fine Art--A Virtual Art Museum: FAQ, Scans

"These images are for study purposes only for students at University of Wisconsin - River Falls. They may not be copied, duplicated, or reproduced."
300 Important Women Artists

"All words and photographs ©1997-1999 Nick Adams unless otherwise noted. All rights reserved. Any use or re-transmission of text, images in this website without written consent of the copyright owner constitutes copyright infringement and is prohibited."
Nick Adams Photography

"The copying of imagesand their subsequent FREE use is permitted with following conditions: that source image(s) clearly indicated recorded by completing our Registration Form. COMMERCIAL in publication Form a licensing fee AUS$100 per image used MUST be paid to CMM BEFORE publication. Warning: Severe penalties exist for non-licensed images. "
Nanoworld Image Gallery--Use of Images

Spiro, Architecture Slide Library, University of California at Berkeley.

Consult:

• Artists Rights Society (40,000 international artists represented)