Red rubber : the story of the rubber slave trade flourishing on the Congo in the year of grace 1906 / by E.D. Morel ; with an introduction by Sir Harry Johnston. Morel, E. D. (Edmund Dene), 1873-1924. Johnston, Harry Hamilton, Sir, 1858-1927. 326.1 MOR London : T. Fisher Unwin, 1906. 1906. 1906 Text xxi, 213 p. : eng Congo (Democratic Republic) History To 1908.