1. Use of underground rock caverns in the world;Bergh-Christensen,1993
2. Storing water in rock caverns is safe and cheap;Broch,1980
3. Singapore—a city of opportunities and challenges;Broms,1989
4. Potential use of underground caverns in Singapore;Broms,1993
5. Rock engineering in Finland;Finish Tunnelling Association (FTA),1986