Preface; A.E. Andersson, Tönu Puu - Economic Analyst and Cultural Activist; M. Beckmann, Tönu Puu and I - In Collaboration; K.-G. Löfgren, Tönu Puu at the Department of Economics, Umeå University -- Microeconomics: Some Reflexions on the Theories of Choice Between Alternative Investment Opportunities; Complementarity, Substitutivity and Regressivity in the Theory of Production; Some Comments on 'Inferior' (Regressive) Inputs; Free Entry and Efficient Distribution of Inputs in a One-product Industry; On the Profitability of Exhausting Natural Resources -- Spatial Economics: Towards a Theory of Optimal Roads; Catastrophic Structural Change in a Continuous Regional Model; Multiplier-accelerator Models Revisited; Pattern Formation in Spatial Economics; The Chaotic Monopolist -- Philosophy of Science: A Graphical Solution of Second-Order Homogeneous Difference Equations; Some Reflections on the Relation Between Economic Theory and Empirical Reality; On Progress and Perfection in the Arts and Sciences -- Curriculum Vitae -- The Collected Scientific Works of Tönu Puu.