s.a. The Witbooi in Southwest Africa during the 19th century. Köln 2007 = 2-06267[in Archiv-Bibliothek]; "Ein Beitrag zur Geschichte d. Witbooischen" by Johannes Olpp, 10 p. hs., 1894; Correspondence with government offices and friendly mission societies about the fate of Witbooi Hottentots e. g. letter of teacher Hendrik Witbooi 1904-1913;

Lay brother, mission building craftsman, 1909 Karibib; curriculum vitae, application, certificates, 1907-1909; letter from Karibib, 1909;

Includes:1. correspondence with Fr. Karl Hoegn, 19192. correspondence with Fr. Ludwig Mekes, 19153. correspondence with Fr. Ronuald Laqua, (1915)4. Correspondence with Brother Peter Staudt, 1918-19195 Correspondence with Fr. Franz Xaver Zeus and Fr. Ernst Ruf (extensive), 1916-1919; Including:- Letter from Fr. Ernst Ruf to Fr. Karl Hoegn, 1915- Letters and experience report from Fr. Simon Rosenhuber, 1914-1916- List of the whereabouts of the confreres and excerpts from letters of some confreres, 1916

Letters and correspondence, 1898-1909; Personal correspondence by Dr. Philipps and a letter by Pastor von Bodelschwingh, 1911, and a newspaper clipping, 1912; family letters, 1914-1919; testimony for Pastor Rösler, 1921; letters from African Christians to Rösler "New Letters from Usambara, 1922

1893-1896 in Okahandja, from 1897 parish office USA and others in Chicago; letters and station reports, 1894-1896; letter from Inspector August Schreiber about dismissal, 1896;