The book "Key Account Management in Business-to-Business Markets" by Stefan Wengler offers a comprehensive analysis and theoretical foundation of Key Account Management (KAM) in B2B markets. It highlights the development and relevance of KAM as an organizational form of marketing management, which has gained importance in recent years. Originally established in the consumer goods industry, KAM has also become prevalent in industrial markets and service-oriented companies to effectively serve key customers. Despite its practical relevance, the implementation and control of KAM in many companies are often inadequately carried out. Wengler develops a decision-support model based on a comparative analysis that enables companies to assess the efficiency of various KAM organizations. This model utilizes criteria from transaction cost theory to provide a sound economic evaluation of KAM alternatives.