1895-1937 in Otjimbingue, Karibib, Praeses and Inspector from 1910; Letters and reports (Presidential files separate), 1895-1910; application for missionary service, curriculum vitae, expert opinion Johannes Georg Heinrich Olpp, 1894; private letters to Inspectors d. RMG, 1895-1899; Instruction for Johannes Georg Heinrich Olpp, 1895; Report on Franz Heinrich Kleinschmidts Death in Otjimbingue, 1896; Overview of the Mountain Damra Church in Otjimbingue, 1896; What drives for faithful work in the mission can the biblical teaching of Christ's Second Coming grant us? Lecture, 12 p., hs., 1898; Lieutenant Kuhn to inspector because of missionary for Karibib, 1901; property case Redecker with sketch, 1904; holiday application Johannes Georg Heinrich Olpp, 1907; plan about Biblical history education to be mastered in the schools, Otjimbingue, 1908; private correspondence from and. with Johannes Georg Heinrich Olpp (partly from the estate), 1928-1948; correspondence with Maria Olpp, née Johannsen (also curriculum vitae and death certificate), 1948-1961; Olpp translated the book "Eine Reise durch Afrika", by J. Du Plessis, 1916, from the Netherlands into German, under the signature 1-02812 in the holdings of the Archive Library ;