1. EN ISO 14688‐1 (2017) Geotechnical Investigation and testing: Identification and classification of soil. Part 1: Identification and description; Benennung Beschreibung Klassifizierung von Boden – Teil 1: Benennung und Beschreibung.
2. EN ISO 14688‐2 (2017) Geotechnical Investigation and testing: Identification and classification of soil. Part 2: Principles for a classification; Benennung Beschreibung Klassifizierung von Boden – Teil 2: Grundlagen der Bodenklassifikation.
3. Deere D.U.;Peck R.B.;Monsees J.E.;Schmidt B.(1969)Design of Tunnel Liners and Support Systems. Report to US.DOT OHSGT Contract 3‐0152. NTIS P183 799.
4. Steiner W.(1996)Criteria for selecting mechanized tunnelling systems in soft ground. Proceedings North American Tunnelling and 22ndAssembly of the International Tunnelling Society Washington PP.483–491.Rotterdam: Balkema.