“…The system with a = τ = 0 is extensively studied in the literature and corresponds to some SCOLE models, where some exponential or polynomial stability results are proved in Chentouf (2003), Chentouf & Wang (2007), Conrad & Morgül (1998), Conrad & Saouri (2002), Littman & Markus (1988), Liu et al (2005), Rao (1995Rao ( , 1998) (for non-linear problems, see, e.g. Gerbi & Said-Houari, 2008;Grobbelaar-Van Dalsen & van der Merwe, 1999).…”