\begin{thebibliography}{1} \bibitem{buhl} H.~R. Buhl. \newblock {\em Creative Engineering Design}. \newblock The Iowa State University Press, 1960. \bibitem{cross} N.~Cross. \newblock {\em Engineering Design Methods}. \newblock John Wiley \& Sons, 1994. \bibitem{dym} C.~L. Dym. \newblock {\em Engineering Design}. \newblock Cambridge University Press, 1994. \bibitem{hubka} V.~Hubka. \newblock {\em Principles of Engineering Design}. \newblock Butterworth Scientific, 1982. \bibitem{ray} R.~C. Johnson. \newblock {\em Mechanical Design Synthesis}. \newblock Robert E. Krieger Publishing Company, 1978. \bibitem{king} W.~R. King. \newblock {\em New Product Development and Introduction}. \newblock McGraw-Hill, 1974. \bibitem{pahl} G.~Pahl and W.~Beitz. \newblock {\em Engineering Design}. \newblock Springer-Verlag, 1991. \bibitem{walton} J.~W. Walton. \newblock {\em Engineering Design}. \newblock West Publishing, 1991. \end{thebibliography}