@article{skonieski_santos_hirsch_rocha_2013,  title={Metallurgical response of an AISI 4140 steel to different plasma nitriding gas mixtures},  volume={16},  ISSN={1516-1439},  url={https://doi.org/10.1590/S1516-14392013005000073},  DOI={10.1590/S1516-14392013005000073},  number={4},  journal={Materials Research},  publisher={ABM, ABC, ABPol},  author={Skonieski, Adão Felipe Oliveira and Santos, Giovanni Rocha dos and Hirsch, Thomas Karl and Rocha, Alexandre da Silva},  year={2013},  month={Jul},  pages={884–890} }