Tompkins, P., & Bird, C. (1991). Secrets of the soil. Viking Arkana.
Lua i Stíl Chicago (17ú heag.)Tompkins, Peter, agus Christopher Bird. Secrets of the Soil. London: Viking Arkana, 1991.
Lua MLA (9ú heag.)Tompkins, Peter, agus Christopher Bird. Secrets of the Soil. Viking Arkana, 1991.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.