Scheffer, C., and P. Heyns. 2001. “Tool Condition Monitoring and Machining Process Optimisation - A Review”. Suid-Afrikaans Tydskrif Vir Natuurwetenskap En Tegnologie / <i>South African Journal of Science and Technology</I&gt; 20 (2), 35-44. https://doi.org/10.4102/satnt.v20i2.249.