1. ASTM. (2006). “Standard practice for determination of the effectiveness of anti-graffiti coating for use on concrete masonry and natural stone surfaces by pressure washing.” D7089-06 West Conshohocken PA.
2. ASTM. (2008). “Standard practice for determination of graffiti resistance.” D6578-08 West Conshohocken PA.
3. British Standards Institution (BSI). (2007). “Natural stone test method: Determination of real density and apparent density and of total and open porosity.” BS EN 1936:2006 London.
4. Bundesanstalt für Straßenwesen [Federal Highway Research Institute] (BASt). (2009). “Technische Prüfvorschriften für Anti-Graffiti-Systeme [Technical testing regulations for anti-graffiti systems].” TP-AGS Technische Lieferbedingungen und Technische Prüfvorschriften für Ingenieurbauten [Technical delivery specifications and technical testing regulations for engineering structures] Bergisch Gladbach Germany (in German).
5. Laser technology for graffiti removal