1. Sharpley, A. N., Daniels, T., Sims, T., Lemunyon, J., Stevens, R. and Parry, R. 2003.Agricultural Phosphorus and Eutrophication,, 2nd ed, 149–44. U. S. Department of Agriculture, Agricultural Research Service, ARS.
2. Why Recover Phosphorus for Recycling, and How?