Private letters, 1890-1893; travelogues, diary notes, correspondence with Trittelvitz, 1905-1914; manuscripts, fragments, diaries, etc.: "The first visit of German children to Queen Msinga of Rwanda, "Back to Queen Msinga, "Observations on the Characteristics of Natives, 1907-1908; General Correspondence and Monthly Reports, 1927-1929; Bugufi calls us - Bugufi needs us, 1929; Letter of Native Christians from Bukoba to the Bishop of Central Tanzania, 1929; Impressions and thoughts during a journey into the landscapes of Mischenye u. Karagwe, 1929; Questionnaires with personal data and birth dates of 14 children, 1930; "Church Mission Society u. Bethel-Bielefeld Mission in Bukoba, German and English version by E. Johanssen, 1930; Correspondence with E. Johanssen, 1930-1933; death notice and memorial certificate, 1934; correspondence with Martha Johanssen, 1934-1940; "On the 100th birthday of E. Johanssen, 1964; "On the 100th birthday of E. Johanssen, by J. Busse, with the addition of Albrecht sen.., 1971

Correspondence, travelogues, working reports, Bukoba station reports, 1928-1931; "The Union Question in East Africa, 7 p., ms. by Heinrich Scholten, 1931; Memorandum of Bethel Mission Bukoba for the British Governor, 1931; New Beginnings in Bukobalande, 3 p., ms., 1931

„Church Mission Society u. Bethel-Mission in Bukoba, 23 S., ms.

Correspondence and Reports, 1910-1917; Report on the current situation and the most important problems of the Rwanda mission by Missionary Roehl, 27 p., ms., 1913; Conference Protocols, 1928-1938; "Church Mission Society and Bethel Mission in Bukoba von Johanssen, 23 p., ms..., 1929; Discussion with Oldham about division of territory, 1930-1931; Minutes of a meeting of the mission societies working in East Africa on 04.07.1932 in Dresden, 1932; The Jubilee Year of our mission society of H. Scholten, 39 p., ms. 1936; "Gedanken zur Begründung einer Eingeborenenkirche Buhaja von H. Scholten, 19 p., ms., 1938; Gemeindeordnung Buhaja, n.J.; Ordnung der Gemeinde- u. Kirchenvertreter-Versammlung in Buhaja, n.J.; Kirchenzuchtordnung, n.J.; Kartenskizzen, n.J.

Statistical material on church, school and medical work in Bukoba, 1926-1938; statistical material on church, school and medical work in Digoland and Usambara, 1932-1939; statistical material on the work of the Bethel Mission, 1949-1970

Correspondence (s.a. M 270), 1896-1897; correspondence, reports, diary excerpts (s.a. M 273) from 1906; Easter sermon in Hohenfriedeberg, 1914; "Vom Schulbau in Mutindili, 1914; Letters by Elfriede Kraemer (stepdaughter of Hosbach) to the Trittelvitz couple, 1912-1914; Hosbach's letters from prisoner of war in Egypt, 1917-1919; "Paulo Shempahila - Lebensbild eines einheimischen Gehilfen, 1919; 3 Songs in Swaheli (Text u. Sheet music by Martha Hosbach), 1927; Letters and reports by Martha Hosbach from 1926; "Die Schule von Kijunga von Josua Hermas, translated by Wilhelm Hosbach, 1932; Jahres-, Konferenz- u. Schulberichte von Bukoba, 1932; Gutachten zur Wasserversorgung in Kigarama, 1932; draft: "Integration of the mission into the German Protestant Church of Knak; "Neue Ordnung für die Missionsarbeiter der Bethel-Mission, 1933; "Ein Wort Dankbarer Erinnerung an Frau Künzel, 1934; Correspondenz während des 2. 1939-1949; letter from an African teacher to Wilhelm Hosbach, 1949; correspondence with the Hosbach couple at home, 1949-1961; obituary for Martha Hosbach, widowed Kraemer, née Wegener; obituary, obituary and memories of Wilhelm Hosbach, 1964