Mahmudah, A. M. H., Syafi’I, D. Handayani, S. J. Legowo, and W. Hartono. “Activity and Time Value of Public Passenger Transportation Users During the Covid-19 Pandemic in 2020 (Bus of Batik Solo Trans Corridor 4 in Surakarta)”. Indonesian Journal of Engineering Research, Vol. 2, no. 2, Nov. 2021, pp. 32-37, doi:10.11594/10.11594/ijer.02.02.01.