1. The application of differential inequalities to the theory of stability;Corduneanu;Am. Sti. Univ. Al. I. Cuza. Lasi.,1960
2. Stability properties and pertubing Liapunov functions;Koksal;J. Applicable Anal.,1992
3. Boundedness properties and perturbing Liapunov functions;Koksal;JMMA,1992