Liu, C., Berg, B., Kutsch, W., Westman, C. J., Ilvesniemi, H., Shen, X., Shen, G., & Chen, X. (2006). Leaf litter nitrogen concentration as related to climatic factors in Eurasian forests. Global Ecology and Biogeography, 15, 438-444. doi:10.1111/j.1466-822x.2006.00251.x.