“…In the case a > 0, the problem (1.1),(1.2) with different boundary conditions and nonlinear terms of different kinds was studied in [5]- [8]. The case of hinged endpoints of the beam u(0, t) = u xx (0, t) = u(π, t) = u xx (π, t) = 0 (1.6) was studied in [5,6]. Equation (1.1) with the conditions u(0, t) = u xx (0, t) = u(π, t) = u x (π, t) = 0, (1.7) under the assumption that the nonlinear term has at most linear growth in u, was considered in [7].…”