Assmer Al – Hayane, M., M. Dawood Al- Bana, K. and H. Ahmed Al-Sowedi, A. (2008) ““ The Transfer of the effect of vertical and inverted vertical learning by using learning tools in learning the skill of sstrike in Volley Ball”, Al-Rafidain Journal For Sport Sciences, 14(48), pp. 115–128. doi: 10.33899/rajsport.2008.50028.