9Allen N. Berger, David B. Humphrey, Efficiency of financial institutions: International survey and directions for future research, European Journal of Operational Research, Volume gs, Issue 2, 16 April 1997, Pages 175 212.
10Kathy Fogel, Randall Morck, Bernard Yeung, Big business stability and economic growth: Is what's good for General Motors good for America? Journal of Financial Economics, Volume 89, Issue 1, July 2008, Pages 83 108.