1970–1980: Interest in investigating and resolving channel structure problems continued to grow in this period. Specifically, the Hartung and Fisher (1965) model was extended to address increasingly complex channel structure, intensity, and selection decisions by Naert and Bultez (1975), Lilien and Rao (1976),and Corstjens and Doyle (1981). But, overall, microeconomic model-based channels research remained relatively sparse in this decade.