I am a Lutheran pastor. We were to use Pieper's four volume set in seminary classes. I already had Mueller. My copy of Pieper was the German edition. I had picked it up at a library cast off sale for ninety cents for the complete four volume set. My German was not sufficient at the time to do my reading assignments from Pieper. I was able to use Mueller for all but one worksheet question. I have used Mueller often over the years. My copy is littered with underlinings and notes, as well as clippings I have pasted into it. Sometimes the proof passages he cites are not always the best and I have made notes on some I think make the point better than those he cites. It is, as other reviewers have noted, a condensed version of Pieper's four volumes. Mueller does use Latin, German, Greek, and Hebrew phrases; but usually follows them immediately with an English translation of the phrases. Still, this may be disconcerting to users who cannot read those languages.