Lange.Oskar. (1971). POLITICAL ECONOMY: PWN- POLISH SCIENTIFIC PUBLISHERS. WARSZAWA.
Chicago-referens (17:e uppl.)Lange.Oskar. POLITICAL ECONOMY: PWN- POLISH SCIENTIFIC PUBLISHERS. panstwowe wydawnictwo naukowe: WARSZAWA, 1971.
MLA-referens (9:e uppl.)Lange.Oskar. POLITICAL ECONOMY: PWN- POLISH SCIENTIFIC PUBLISHERS. WARSZAWA, 1971.