The "BISCHOFF Concordance" is an archive and reference work in one. It contains the publications "Catechism", "Song Concordance to the Hymnal", "Lyrics from the Choir Book", "Teaching and Knowledge", "The Bible (Luther Bible 2017)", "Guiding Principles" and "Our Family". The app including catechism is free. The other modules can be purchased in the shop of the BISCHOFF publishing house. You are completely free in your decision which modules you want to purchase: Install the free app and add on