20thcentury 330 civilization commerce econometricmodels economicaspects economics energyconsumption entropy environmentalaspects environmentalpolicy equilibrium(economics) france governmentpolicy history humanecology industries internationaltrade landuse management mathematicalmodels naturalresources outdoorrecreation petroleumindustryandtrade philosophy politicalaspects politicalparticipation rationalexpectations(economictheory) scarcity socialaction unitedstates