Note on a paper of E. M. E. Zayed and S. F. M. Ibraham (Q1205624)

\textit{E. M. E. Zayed} and \textit{S. F. M. Ibrahim} [Int. J. Math. Math. Sci. 12, No. 2, 341-348 (1989; Zbl 0693.34022)] considered a boundary eigenvalue problem for a fourth order differential equation. They assert that the eigenvalues are positive and tend to \(\infty\). The authors of the present note show that this is wrong; indeed, the eigenvalues are asymptotically located around the negative real axis. As is pointed out, the error is due to the fact that an additional auxiliary boundary condition is introduced and that this eigenvalue problem has at most finitely many eigenvalues.