APA
Halecki O., . (1943). A history of Poland. New York: Roy Publishers.
Chicago
Halecki Oskar, . 1943. A history of Poland. New York: Roy Publishers.
Harvard
Halecki O., . (1943). A history of Poland. New York: Roy Publishers.
MLA
Halecki Oskar, . A history of Poland. New York: Roy Publishers. 1943.
