On The Path to Enlightenment, by Helmut Uhlig

Documentation of the famous Berti Aschmann collectio, now on display in the Rietberg Museum.
The english version of this catalogue had a small prinrun, and is long out of print, and hard to find.

A second volume has been published later by Heidi von Schroeder;
as far as I know, never published in english (the german version is available here in the shop,
at a modest price ...