http://www.musicated.com/CGCL/music/CGCL_az.html#C

http://www.delcamp.net/nl/index.html

http://www.muslib.se/ebibliotek/boije/indexeng.htm

http://www.earlyromanticguitar.com/

http://www.graphicguitars.com/

http://eu.art.com/gallery/id--b156120-c23945/guitars-decorative-art-art-prints.htm?pg=5

http://catalog.wustl.edu/search/aGeorge+C.+Krick+Collection+of+Guitar+Music,+Collec/ageorge+c+krick+collection+of+guitar+music+collection/-3,-1,0,B/exact&FF=ageorge+c+krick+collection+of+guitar+music+collection&1,226,

http://www.musikwissenschaften.de/service/nb/index.htm