http://www.simplicissimus.info/ – A German website with devoted to the periodicals Simplicissimus and Jugend with an archive of digitized issues.
http://richet.christian.free.fr - A french site with probably the most comprehensive catalogue of Alfonse Mucha’s work.
http://www.klimt.com/ - A virtual museum devoted to the work of Gustav Klimt.
http://www.dellaquila.net/RKweb/default.htm- A website devoted to the postcards of Raphael Kirchkner.
http://www.orlikprints.com/- A showcase of Emil Orlik’s prints.
http://www.franzvonstuck.com/ -A great website featuring Jack Daulton’s collection Franz Von Stuck works.
http://www.jan-toorop.com/- The Jan Toorop research centre with a vast image library of his works.
http://www.leopoldmuseum.org/en - The Leopold Museum in Vienna specializing in Klimt, Egon Schiele, Kokoschka and the Vienna Secession.
http://www.neuegalerie.org/ - America’s answer to the Leopold Museum. Superb collection of Klimt and Schiele.
http://gallery.albertina.at/eMuseum/code/emuseum.asp?style=Browse¤trecord=1&page=collections&profile=objectsde&newvalues=1&newpage=collections#posters - The Albertina Museum in Vienna has an Picture Database of Austrian Graphic art.