@article{article31510aca,
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},
author = {Meza, Juan Manuel and Moré Farías, María Cristina and Souza, Roberto Martins de and Cruz Riaño, Luis Javier},
year = {2007},
doi = {10.1590/s1516-14392007000400019},
journal   = {Materials Research}
}