Several interesting, in my opinion, references to materials on the history and technology of restoration of the frescoes (and not only):
The site contains collection of icons, mosaics, frescoes, miniatures, draw and transfers ordered by the iconography (the image of the Savior, the Virgin Mary and various saints, the Bible and Gospels, etc.), icon painters, schools, location. Separately considered the most famous Deesis and holidays ranks. In the "Library" project to collect sets of thematic publications, and discussion of issues related to the Orthodox art, visitors can conduct the forum.
http://www.icon-art.info/index.php?lng=ru
Information portal Hramdekor "Everyone who is engaged in church art"
http://hramdecor.ru/
Site dedicated to the art of restoration. This is an informational field to find and solve many problems in the restoration, the interaction of professionals and interested users in the community of restorers.
http://www.art-con.ru/node/64