Shepard, P., & McKinley, D. (1971). Environmental essays on the planet as home. Houghton-Mifflin.
Lua i Stíl Chicago (17ú heag.)Shepard, Paul, agus Daniel McKinley. Environmental Essays on the Planet as Home. Boston: Houghton-Mifflin, 1971.
Lua MLA (9ú heag.)Shepard, Paul, agus Daniel McKinley. Environmental Essays on the Planet as Home. Houghton-Mifflin, 1971.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.