“…External reasons Taylor (1995), Tsiotras and Gotzamani (1996), Huarng et al (1999), Escanciano et al (2001), Gustafson et al (2001), Mathews et al (2001), Poksinska et al (2002), Corbett et al (2003), Heras et al (2006), Prajogo (2009), Beattie and Sohal (1999), Lee and Palmer (1999), Withers and Ebrahimpour (1996), Fuentes et al (2000), Torre et al (2001), Sun and Cheng (2002), Magd and Curry (2003), Heras-Saizarbitoria et al (2011), Carlsson and Carlsson (1996), Lipovatz et al (1999), Anderson et al (1999), Buttle (1997) (2001), Sun and Cheng (2002), Taylor (1995), Idris et al (1996), Tsiotras and Gotzamani (1996), Skrabec et al (1997), Escanciano et al (2001), Magd and Curry (2003), Prajogo (2009), Gotzamani and Tsiotras (2002), Heras et al (2006), HerasSaizarbitoria et al (2011), Withers and Ebrahimpour (1996), Huarng et al (1999), Lee and Palmer (1999), Withers and Ebrahimpour (2000), Carlsson and Carlsson (1996), …”