“…For the case without source term in (1.4), it is known that the damping term assures the global existence of solutions for (1.4), for example, see [1], [2], [4], [13], [16]. For the analysis of the interaction between various damping and source terms in (1.4), we refer the reader to [5], [8], [10], [11], [19], [26], [28] and the references therein. It is worth noting that k = 0 in (1.1) the corresponding problem can be solved by monotonicity argument and approaches in [11].…”