World Tunnel Congress '99 Oslo, Norway, & Alten, T. (1999). Challenges for the 21st century: Proceedings of the World Tunnel Congress '99, Oslo, Norway, 31 May-3 June 1999. Balkema.
Chicago Style (17th ed.) CitationWorld Tunnel Congress '99 Oslo, Norway, and T. Alten. Challenges for the 21st Century: Proceedings of the World Tunnel Congress '99, Oslo, Norway, 31 May-3 June 1999. Rotterdam ; Brookfield: Balkema, 1999.
MLA (9th ed.) CitationWorld Tunnel Congress '99 Oslo, Norway, and T. Alten. Challenges for the 21st Century: Proceedings of the World Tunnel Congress '99, Oslo, Norway, 31 May-3 June 1999. Balkema, 1999.
Warning: These citations may not always be 100% accurate.