Skinner, B. J. (1976). Earth resources (2nd ed.). Prentice-hall.
Lua i Stíl Chicago (17ú heag.)Skinner, Brian J. Earth Resources. 2nd ed. Englewood Cliffs, N. J: Prentice-hall, 1976.
Lua MLA (9ú heag.)Skinner, Brian J. Earth Resources. 2nd ed. Prentice-hall, 1976.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.