There are two paths to obtaining copyright clearance. You may either contact the copyright holder*, or go through a company that processes copyright permissions, such as CCC (Copyright Clearance Center).
* Many times the copyright holder’s identity is not clear from the book, article, artwork, etc. as current copyright law does not necessitate that copyright be marked or the copyright owner be cited; in that case, contact the publisher and/or the author.
- Sample copyright permission request letter (MSWord)
- CCC web site: http://www.copyright.com