1. GLOBAL NONEXISTENCE OF SOLUTIONS TO SYSTEM OF KLEIN-GORDON EQUATIONS WITH DEGENERATE DAMPING AND STRONG SOURCE TERMS IN VISCOELASTICITY. Authors: FARES YAZID, DJAMEL OUCHENANE, KHALED ZENNIR.2. GLOBAL NONEXISTENCE OF SOLUTION FOR COUPLED NONLINEAR KLEIN-GORDON WITH DEGENERATE DAMPING AND SOURCE TERMS. Authors: DJAMEL OUCHENANE, ZINEB KHALILI, FARES YAZID.