“…Closed-form solutions are only presented with the assumption of independence by Li and Ng (2000), Zhu et al (2004), Yan et al (2009Yan et al ( , 2012, Yu et al (2010Yu et al ( , 2012, Wu and Li (2012), Li and Li (2012). For more general models, the solution is frequently determined by a numerical procedure (see e.g., van Binsbergen and Brandt, 2007;Mansini et al, 2007;Gülpınar and Rustem, 2007;Zhang et al, 2012Liu et al, 2012Liu et al, , 2013Köksalan and Şakar, 2014).…”