APA
Gregersen E., . (1977). Language in Africa. New York: Gordon and Breach.
Chicago
Gregersen Edgar, . 1977. Language in Africa. New York: Gordon and Breach.
Harvard
Gregersen E., . (1977). Language in Africa. New York: Gordon and Breach.
MLA
Gregersen Edgar, . Language in Africa. New York: Gordon and Breach. 1977.