Farrell, M., Hill, P. W., Farrar, J., Deluca, T. H., Roberts, P., Kielland, K., Dahlgren, R., Murphy, D. V., Hobbs, P. J., Bardgett, R. D. and Jones, D. L. 2013. Oligopeptides represent a preferred source of organic N uptake: a global phenomenon? Ecosystems. 16, pp. 133-145. https://doi.org/10.1007/s10021-012-9601-8
Turnbull, L., Wainwright, J., Brazier, R. E. and Bol, R. 2010. Biotic and abiotic changes in ecosystem structure over a shrub-encroachment gradient in the southwestern USA. Ecosystems. 13, pp. 1239-1255. https://doi.org/10.1007/s10021-010-9384-8