“…On the existence and the controllability for these equations, we refer the reader to (e.g. see Chang, 2007;Chang, Anguraj, & Arjunan, 2008;Karthikeyan & Balachandran, 2009Park, Balachandran, & Annapoorani, 2009;Park, Balasubramaniam, & Kumaresan, 2007;Shen & Sun, 2012;Yan & Yan, 2013, and the references therein).…”