Syafyudin, B. A., rizal Rizal, and wandi Rusfiandi. “THE USE OF COCONUT SHELL CHARCOAL AS AN ADDED MATERIAL TO THE CONCRETE MIX OF Fc’ 14,53 MPa”. RETENSI, Vol. 1, no. 2, June 2021, pp. 43-49, doi:10.31573/retensi.v1i2.321.