Complex sentence: UNESCO, Eolss Publishers, Oxford, UK is a multidisciplinary, macro-scale approach to world history and social change that stresses that the world-system (and not nation states) should be the primary (but not exclusive) unit of social analysis.
Split into simpler sentences: UNESCO, Eolss Publishers, Oxford, UK is a multidisciplinary, macro-scale approach to world history and social change. World-systems analysis stresses that the world-system (and not nation states) should be the primary (but not exclusive) unit of social analysis.