Dreus, A., Kozhevnikov, A., Lysenko, K. and Sudakov, A. 2016. Investigation of heating of the drilling bits and definition of the energy efficient drilling modes. Eastern-European Journal of Enterprise Technologies. 3, 7(81) (Jun. 2016), 41–46. DOI:https://doi.org/10.15587/1729-4061.2016.71995.