Tash, M. M., and S. A. Alkahtani,  "Effect of heat treatment Hardness of Al-Cu-Mg-Li-Zr , Al-Mg-Si  and Al-Mg-Zn alloys- Experimental Correlation Using Factorial DOE and ANOVA Methods",  Advanced Materials Research Journal (AMR) at www.scientific.net © (2015) Trans Tech Publications, vol. 881-883 , pp. 1317-1329, 2014.