Hakim, S. N., Kalijaga, A. and Indrawati, S. (2020) “SERVICE PERFORMANCE IMPROVEMENT DURING PANDEMIC COVID 19 USING INTEGRATED SERVQUAL AND SIX SIGMA: TELECOMMUNICATION AND INFORMATION INDUSTRY CASE APPLICATION”, Journal of Industrial Engineering and Halal Industries, 1(2), pp. 94–101. doi: 10.14421/jiehis.2198.