@article {565, title = {Phosphorus and nitrogen limitation of phytoplankton growth in the freshwaters of North America: a review and critique of experimental enrichments}, journal = {Canadian Journal of Fisheries and Aquatic Sciences }, volume = {47}, year = {1990}, pages = {1468-1477}, author = {Elser, J.J. and Marzolf, E.R. and Goldman, C.R.} }