I got into the music of cluster through Julian Cope's book of course. However I was not expecting it at all to be like this. This is actually the kind of German rock that influenced everybody back in the 70's: Eno etc would follow these footsteps a few years later. This group really laid the foundations for ambient music in a way that I did not really expect. It is much different from the Kluster stuff that has not aged so well. However even if it is slightly pricey today it is worh the effort to look into.