Graebner advanced a theory of diffusion of culture (Kulturkreise) which became the basis of a culture-historical approach to ethnology. His theories had influence for a time in the field of ethnology, and were also propounded by Franz Boas, Clark Wissler and Paul Kirchhoff. He was in Australia attending an anthropological conference when World War I broke out in 1914, and due to accusations of having hidden certain sensitive documents he was not allowed to leave Australia for the duration of the war.
^Gaillard, Gérald (2004). The Routledge Dictionary of Anthropologists. Peter James Bowman (trans.) (English translation of Dictionnaire des ethnologues et des anthropologues  ed.). London and New York: Routledge. pp. 43–44. ISBN0-415-22825-5. OCLC52288643.