1. Anatolian motorway, Gumusoa Gerede section 2;Astaldi;Geological Report,1993
2. Geotehnical measurements results;Astaldi,1997
3. Geotechnical measurements results;Astaldi,1998
4. A critical approach to the new Austrian tunneling method in Bolu tunnels;Aygar,2000
5. Investigation of the Bolu Tunnel stability by means of static and dyanamic analyses;Aygar,2007