Cohen, M. R. (1991). Discover science. Scott, Foresman and Comp.
Lua i Stíl Chicago (17ú heag.)Cohen, Michael R. Discover Science. Scott, Foresman and Comp, 1991.
Lua MLA (8ú heag.)Cohen, Michael R. Discover Science. Scott, Foresman and Comp, 1991.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.