With a Probability of Being Seen. Dorothee and Konrad Fischer: Archives of an Attitude (Richter Verlag) is a catalog of the Fischer gallery and collection (DAP; Amazon).
There are contributions from Rudi Fuchs, Thomas Kellein, Friedrich Meschede, Roland Mönig, and Guido de Werd. After showing last fall at MACBA in Barcelona, the exhibition moved in winter to the Museum Kurhaus in Kleve.
Catalog essays are online: Friedrich Meschede, “The freedom of silence – or the attempt at making a portrait from archival ephemera,” and Roland Mönig, “From Carl Andre to Gregor Schneider: The Dorothee and Konrad Fischer Collection”; also the press release (PDF).
There is audio online from Brigitte Kölle, Friedrich Meschede and Dorothee Fischer, as well as lectures by Jürgen Harten, “Die Ausstellungen der Reihe Prospect (1968-1976),” and Lynda Morris, “Unconcealed. Konrad Fischer and the Conceptual Art Network 1967-1977.”
Also a YouTube video.