Portwood, M. E., & Portwood, T. B. (1977). Our nation's story. Steck-Vaughn.
Lua i Stíl Chicago (17ú heag.)Portwood, Mary E., agus Thomas B. Portwood. Our Nation's Story. Austin: Steck-Vaughn, 1977.
Lua MLA (8ú heag.)Portwood, Mary E., agus Thomas B. Portwood. Our Nation's Story. Steck-Vaughn, 1977.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.