1. ABAQUS. Theory Manual, Version 5.8, Hibbit, Karlsson & Sorensen Inc. (1998)
2. Aifantis, E.C.: Update on class of gradient theories. Mechanics of Materials 35(3), 259–280 (2003)
3. Akkermann, J.: Rotationsverhalten von Stahlbeton-Rahmenecken. PhD Thesis, Universität Fridericiana zu Karlsruhe, Karlsruhe (2000)
4. Asferg, P.N., Poulsen, P.N., Nielsen, L.O.: Modelling of crack propagation in concrete applying the XFEM. In: Meschke, G., de Borst, R., Mang, H., Bicanic, N. (eds.) Computational Modelling of Concrete Structures, EURO-C, pp. 33–42. Taylor and Francis (2006)
5. Askes, H., Sluys, L.J.: A classification of higher-order strain gradient models in damage mechanics. Archive of Applied Mechanics 53(5-6), 448–465 (2003)