David C. C. Ng, and Simon Y. H. Low. “Singapore Case Histories on Omission of Strut by Observation Approach For Circle Line and Down Town Line Projects”. Geotechnical Engineering Journal of the SEAGS & AGSSEA, vol. 47, no. 3, Oct. 2024, pp. 51-61, doi:10.14456/seagj.2016.24.