1
Published: 1889
2
Published: 1885
3
Published: 1886
Superior document: The Congo and the founding of its free state a story of work and exploration ; in two volumes ; wuth over one hundred full-page and smaller illustrations, two large maps and several smaller ones Vol. II
4
Published: 1886
Superior document: The Congo and the founding of its free state a story of work and exploration ; in two volumes ; wuth over one hundred full-page and smaller illustrations, two large maps and several smaller ones Vol. I