Wassmann, Dietrich. Pionierdienst unter den Galla in Westabessinien [Pioneer service among the (Oromo) in western Abyssinia]. Hermannsburg: Missionsbuchhandlung, 1938.
(1) English translation (excerpt)
(2) German text
(3) Oromo passion story of Jesus
Beginning of the passion story of Jesus
(translated by Wassmann for the Lenten liturgy):
Pionierdienst, opp. p. 80