McKnight, T. L., & Lindgren, P. C. (1990). Physical geography: A landscape appreciation (3rd ed.). Prentice-Hall.
Lua i Stíl Chicago (17ú heag.)McKnight, Tom L., agus Patricia Caldwell Lindgren. Physical Geography: A Landscape Appreciation. 3rd ed. Englewood Cliffs, N.J: Prentice-Hall, 1990.
Lua MLA (9ú heag.)McKnight, Tom L., agus Patricia Caldwell Lindgren. Physical Geography: A Landscape Appreciation. 3rd ed. Prentice-Hall, 1990.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.