1. Foster , R. , 1986 ,Innovation – The Attacker's Advantage, Summit Books , New York , 316 pp.
2. France . Paul , 1996 ,Engineering Creativity, Chemical Engineering , February 1996 . pp. 113 – 114 .
3. Howard , W.G. and Guile , B.R. Ed. 1992 ,profiting from Innovation.the Free Press . New York . 154 pp.