GUTH, H. P., & SHNIDER, P. S. (1981). Our world today. D.C. Heath.
Lua i Stíl Chicago (17ú heag.)GUTH, Hans P., agus Patricia S. SHNIDER. Our World Today. Lexington: D.C. Heath, 1981.
Lua MLA (9ú heag.)GUTH, Hans P., agus Patricia S. SHNIDER. Our World Today. D.C. Heath, 1981.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.