@article{lleras_1977,  title={Differences in stomatal number per unit area within the same species under different micro-environmental conditions: A working hypothesis},  volume={7},  ISSN={0044-5967},  url={https://doi.org/10.1590/1809-43921977074473},  DOI={10.1590/1809-43921977074473},  number={4},  journal={Acta Amazonica},  publisher={Instituto Nacional de Pesquisas da Amazônia},  author={Lleras, Eduardo},  year={1977},  month={Oct},  pages={473–476} }