Heller, H. R. (1973). International trade: Theory and empirical evidence (2d ed.). Prentice-Hall.
Lua i Stíl Chicago (17ú heag.)Heller, H. Robert. International Trade: Theory and Empirical Evidence. 2d ed. Englewood Cliffs, N.J.: Prentice-Hall, 1973.
Lua MLA (8ú heag.)Heller, H. Robert. International Trade: Theory and Empirical Evidence. 2d ed. Prentice-Hall, 1973.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.