Quattroblok is applied to the Wave run-up zone on the Afsluitdijk. The XblocPlus is also used in the Vistula Spit canal in Poland. See also References British Standards, BS 6349 Code of Practice for Maritime Structures, Part 7, Guide to design & construction of Breakwaters, 1991. CIRIA/CUR, Rock Manual, 2007 2 Research Articles on the Development and Design of Xbloc Breakwater Armour Units 3 H.J. Verhagen, Classical, Innovative and Unconventional Coastline Protection Methods, Coastal Engineering section, Delft University of Technology, the Netherlands, 2004 4 ASCE Specialty Conference, Washington D.C. March, Seabees in Service, 1983 External links Delta Marine Consultants Xbloc design guidelines Rock Manual 2007 MEDUS (Maritime Engineering Division University Salerno) Coastal engineering Wave-dissipating concrete blocks