Shenton, J. P., & Meckler, A. M. (1973). Programmed learning aid for United States history. Learning Systems.
Lua i Stíl Chicago (17ú heag.)Shenton, James Patrick, agus Alan M. Meckler. Programmed Learning Aid for United States History. Homewood, Ill: Learning Systems, 1973.
Lua MLA (9ú heag.)Shenton, James Patrick, agus Alan M. Meckler. Programmed Learning Aid for United States History. Learning Systems, 1973.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.