If you have only a signature or initials and cannot identify the artist, consult an online site that archives artist's signatures such as:

http://www.artarchiv.net/doku/artistsignatures.htm

http://www.signaturehelp.com

or an artist signature or monogram dictionary such as:

Encyclopedia of Artists' Signatures, Symbols & Monograms by H.H. Caplan and Bob Creps, Dealer's Choice Books, Land O' Lakes, FL, 1999

Classified Dictionary of Artists Signature, Symbols and Monograms, by H.H. Caplan, Gale Publishing, Detroit, 1976

American Artists: Signatures and Monograms, 1800–1989, Castagno, John, ed. Metuchen, N.J.: Scarecrow Press, 1990.

Artists as Illustrators: An International Directory with Signatures and Monograms 1800 to the Present, John Castagno, ed., Metuchen, N.J.: Scarecrow Press, 1990.

Dictionary of Signatures and Monograms of American Artists, Peter Hastings Falk, ed,. Madison, Conn.: Sound View Press, 1988.

The Visual Index of Artists' Signatures and Monograms, Radway Jackson, ed, London: Cromwell Editions, 1991.

This list in NOT definitive. Any suggestions or additions to this page will be much appreciated!