Trefry, David and Trefry, J. F. 1967. Kuman Language Course. Port Moresby, Papua New Guinea: Summer Institute of Linguistics.
@book{Trefry-and-Trefry-1967, address = {Port Moresby, Papua New Guinea}, author = {Trefry, David and Trefry, J. F.}, publisher = {Summer Institute of Linguistics}, title = {Kuman Language Course}, year = {1967} }