Heilbroner, R. L. (1970). The economic problem (2nd ed.). Prentice-Hall.
Lua i Stíl Chicago (17ú heag.)Heilbroner, Robert L. The Economic Problem. 2nd ed. Englewood Cliffs, N.J: Prentice-Hall, 1970.
Lua MLA (9ú heag.)Heilbroner, Robert L. The Economic Problem. 2nd ed. Prentice-Hall, 1970.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.