E. Fischer, D. Killmann, and U. Meve, “Neoschumannia gishwatiensis (Apocynaceae, Asclepiadoideae-Ceropegieae) from Gishwati Forest, Rwanda—a third and new species from a disjunct African genus”, Phytotaxa, vol. 77, no. 2, pp. 19–26, Jan. 2013.