Artists Rights Society – Copyright and license monitoring organization. Great reference to use if you need to ask about image usage.

Asking For Permissions – Columbia University guide to asking permission to use a copyrighted work from the rights holder. Advice on contacting the rights holder and writing and letter.

Boston University Research Guide for Copyright – Very helpful compilation of resources on copyright and image use.

CAA – (College Art Association) Fair Use Guide.

Creative Commons – Useful information of usage, sharing and remixing works. Many images online and in Wikipedia are covered under a specific CC license. You can use this resource to find out if you can use an image.

Grad Student Guide to Copyright – from the University of Michigan.

Public Domain Sherpa – Guide to use of Public Domain and Copyrighted work.

US Copyright Office Compendium for Visual Art Works –  Covers the copyright for different kids of visual art works.

Visual Resource Association Statement on the Fair Use of Images for Teaching, Research, and Study – Six uses of copyrighted still images that the VRA believe fall within the U.S. doctrine of fair use.