1. Torrent R, Fernandez Luco L (editors). Non-destructive evaluation of the penetrability and thickness of the concrete cover. France: State-of-the-Art-Report, RILEM TC 189-NEC, RILEM Publications S.A.R.L.; 2007. 223 pp.
2. EN-206:2013. Concrete: specification, performance, production and conformity. European Standard, CEN; 2013.