1. Allen, S. E. (1989). Analysis of vegetation and other organic materials. In S. E. Allen (Ed.), Chemical analysis of ecological materials (3rd ed., pp. 46–60). Oxford, England: Blackwell Scientific Publications.
2. Bettez, N. D., Marino, R., Howarth, R. R., & Davidson, E. A. (2013). Roads as nitrogen deposition hot spots. Biogeochemistry, 114(1–3), 149–163.
3. Davis, A., Shokouhian, M., & Ni, S. (2001). Loading estimates of lead, copper, cadmium, and zinc in urban runoff from specific sources. Chemosphere, 44(5), 997–1009.
4. Epstein, E., & Bloom, A. J. (2005). Mineral nutrition of plants: principles and perspectives (2nd ed.). Sunderland: Sinauer Associates Inc.
5. Forman, R. T. T., Sperling, D., Bissonette, J. A., Clevenger, A. R., Cutshall, C. D., Dale, V. H., Fahrig, L., France, R., Goldman, C. R., Heanue, K., Jones, J. A., Swanson, F. J., Turrentine, T., & Winter, T. C. (2003). Road ecology: Science and solutions. Washington D.C.: Island Press.