online
masterprints catalogues
2000
PETER HELM CATALOGS
Alliance Polygraficum
At Polygraphicum
Google1st
0700Polygraf
0700 76594723
https://web.archive.org/web/20091116221349/http://www.polygraphicum.de/artPOLYGRAPHICUMbookGESAMTKATALOG.html