91B02 Fundamental topics (basic mathematics, methodology; applicable to economics in general)
91B06 Decision theory [See also 62Cxx, 90B50, 91A35]
91B08 Individual preferences 
91B10 Group preferences 
91B12 Voting theory
91B14 Social choice 
91B16 Utility theory 
91B18 Public goods
91B24 Price theory and market structure 
91B26 Market models (auctions, bargaining, bidding, selling, etc.)
91B28 Finance, portfolios, investment
91B30 Risk theory, insurance
91B32 Resource and cost allocation
91B38 Production theory, theory of the firm
91B40 Labor market, contracts
91B42 Consumer behavior, demand theory
91B44 Informational economics
91B50 Equilibrium: general theory
91B52 Special types of equilibria
91B54 Special types of economies
91B60 General economic models, trade models
91B62 Dynamic economic models, growth models
91B64 Macro-economic models (monetary models, models of taxation)
91B66 Multisectoral models
91B68 Matching models
91B70 Stochastic models
91B72 Spatial models
91B74 Models of real-world systems
91B76 Environmental economics (natural resource models, harvesting, pollution, etc.)
91B82 Statistical methods; economic indices and measures
91B84 Economic time series analysis [See also 62M10]
91B99 None of the above, but in this section