O’Brien, Daniel P.
1997
Vertical Integration in Magill, Frank N. ~ International Encyclopedia of Economics
Volume One
Fitzroy Dearborn Publishers; London, Chicago
pp. 1628-1631

1628
Definition-vertical integration:
“Vertical integration is a situation in which a single firm owns and controls portions of successive stages of production. The extent of integration, through its effect on firms’ costs and managerial incentives, is an important determinant of firms’ profitability and overall industry performance.”