A&A 1942 2nd ed: Is it necessary to build an industrial complex in order to mobilize units?
If you look at the setup charts for each country, some territories have "Industrial Complex" listed of one of the units to be placed.  I suspect that they were not printed directly on the board because they could then get covered up by other pieces.

You can find a copy of the setup charts at 
http://www.axisandallies.org/resources-downloads/setup-chart-axis-allies-1942-second-edition/