1. Audit Commission Hong Kong. Report of the Director of Audit (Report No. 49)., 2007, Audit Commission, Hong Kong, 1–2, Ch. 11.
2. BSI. BS 3811:1993: Glossary of terms used in terotechnology. 1993, BSI, London, UK,
3. Cassimatis P . A Concise Introduction to Engineering Economics., 1992, E and FN Spon, London, UK: 166.
4. Chen WF , Duan L . Bridge Engineering: Construction and Maintenance., 2003, CRC Press, Boca Raton, FL, USA, 5–8.