Schor, H. J., & Gray, D. H. (2007). Landforming: An environmental approach to hillside development, mine reclamation and watershed restoration. John Wiley & Sons.
Lua i Stíl Chicago (17ú heag.)Schor, Horst J., agus Donald H. Gray. Landforming: An Environmental Approach to Hillside Development, Mine Reclamation and Watershed Restoration. Hoboken, N.J: John Wiley & Sons, 2007.
Lua MLA (9ú heag.)Schor, Horst J., agus Donald H. Gray. Landforming: An Environmental Approach to Hillside Development, Mine Reclamation and Watershed Restoration. John Wiley & Sons, 2007.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.