Dechant, B., et al. (2017). "Estimation of photosynthesis traits from leaf reflectance spectra: Correlation to nitrogen content as the dominant mechanism." Remote Sensing of Environment 196: 279-292. Photosynthetic traits has its mechanism by leaf internal components. Comparing the spectroscopic absorption of causing components and their traits, they can be detected and correlation. In the case of Vcmax, N dominantly controls it.