APA
Hirschfeld C., Knoebel E. E., . (1980). The modern world. New York: Harcourt Brace Jovanovich.
Chicago
Hirschfeld Charles, Knoebel Edgar E, . 1980. The modern world. New York: Harcourt Brace Jovanovich.
Harvard
Hirschfeld C., Knoebel E. E., . (1980). The modern world. New York: Harcourt Brace Jovanovich.
MLA
Hirschfeld Charles, Knoebel Edgar E, . The modern world. New York: Harcourt Brace Jovanovich. 1980.