... The total of 953 identified studies decreased to 949 after the exclusion of repeated studies. After the abstracts of these 949 studies were reviewed, 94 were retrieved; of these, 36 studies met the inclusion criteria and were included in the review (Ahmad-Stout et al., 2018;Odwe et al., 2018;Gennari et al., 2017;Nam et al., 2017;Wachter et al., 2017;Holtmann, 2016;Kalunta-Crumpton, 2016;Um et al., 2016;Usta et al., 2016;Kim and Sung, 2015;Parcesepe et al., 2015;Sipsma et al., 2015;Wako et al., 2015;Akhter and Kusakabe, 2014;Wirtz et al., 2014;Kyriakakis, 2014;Moya et al., 2014;Akinsulure-Smith et al., 2013;Fisher, 2013;Kalunta-Crumpton, 2013;Reina et al., 2013;Wirtz et al., 2013;Feseha et al., 2012;Fuchsel et al., 2012;Keygnaert et al., N. Daoud 2012;Zakar et al., 2012;Zannettino, 2012;Anitha, 2011;Earner, 2010;Horn, 2010;Jin and Keat, 2009;Ahmad et al., 2009;Erez et al., 2009;Bui and Morash, 2008;Morash et al., 2007;Thapa-Oli et al., 2008) -see Figure 1. ...