1892-1918 in Otjihaena, Gaub, Tsumeb; Letters, quarterly and station reports, 1891-1918; private letters to inspectors of the RMG, 1892-1900; letter from and contract with chief Kahimemua, 1892; printed municipal journal "Omahunge" in Herero language by Ferdinand Lang, 1900; application to d. Imperial Gouvernement in Windhoek for establishing 4 locations, 1902; medical testimony for Mrs. Maria Lang, née Müller, 1904; justification of Ferdinand Lang against accusations by missionary Friedrich Hermann Rust, 1906; legal dispute with the Otavi Mine and Railway Company, 1913; report by daughter Lydia Lang about the death of her parents, 1918; correspondence with the children Lang, 1942;

1892-1904 in Zumamas, Gaub, Grootfontein, Otjimbuna, Franzfontein; letters, travel, station and annual reports, 1891-1904; private letters to inspectors of the RMG, 1891-1899; map sketch with location of residential places in the Otavi area, 1894; letter of the. Teacher Hendrik Djuella, 1901; Letters from Emmy Kremer, née Weyel with reports of her husband's death, 1904; Address by G. D. J. Scholls and Johs. G. de Wet at the funeral of Friedrich Kremer in Grootfontein, 1904; obituary for Emmy Kremer, née Weyel, 1935;