Alt, . H. . “Ansa Metallocene Complexes of Zirconium and Hafnium With –SiMe2-1,2-C6H4-CH2- Bridged Indenyl Ligands As Catalyst Precursors for Homogeneous Ethylene Polymerization”. Jordan Journal of Chemistry (JJC), vol. 11, no. 3, Sept. 2016, pp. 147-5, https://jjc.yu.edu.jo/index.php/jjc/article/view/104.