Mohamad, W. F., A. A. Khan, F. Ahmad, and A. Yassin. “Phase Analysis and Microstructure Study of Sintered Ni-Cr Composites Containing MoS2, Ag and CaF2 Additives As Solid Lubricants”. Journal of Mechanical Engineering and Sciences, Vol. 14, no. 2, June 2020, pp. 6548 -56, doi:10.15282/jmes.14.2.2020.02.0514.