“…Therefore, we only give some references e.g. Zeng et al 2015, Zhang et al (2013), Neitzel (2010), Neitzel and Schaffrin (2016), Snow and Schaffrin (2012), Shen et al (2011), Schaffrin et al (2014), Schaffrin and Felus (2008), Mahboub (2012Mahboub ( , 2014Mahboub ( , 2016, Mahboub et al (2012Mahboub et al ( , 2015, Mahboub and Sharifi (2013a, b), Paláncz and Awange (2012), Amiri-simkooei and Jazaeri (2012), Fang (2011Fang ( , 2013Fang ( , a, b c, 2015, Fang et al ( , 2016, Lu et al (2014), Zhou and Fang (2015) and Fang and Wu (2015) etc. In the rest of this paper we define these two parts for a DEIV model.…”