@article{meza_farias_souza_riaño_2007,  title={Using the ratio: maximum load over unload stiffness squared, Pm/Su², on the evaluation of machine stiffness and area function of blunt indenters on depth-sensing indentation equipment},  volume={10},  ISSN={1516-1439},  url={https://doi.org/10.1590/S1516-14392007000400019},  DOI={10.1590/S1516-14392007000400019},  number={4},  journal={Materials Research},  publisher={ABM, ABC, ABPol},  author={Meza, Juan Manuel and Farias, María Cristina Moré and Souza, Roberto Martinz de and Riaño, Luis Javier Cruz},  year={2007},  month={Oct},  pages={437–447} }