"[...] this study provides an extensive overview of conceptualizations and operationalizations of media diversity in different fields using a systematic literature review (1999–2018). This showed a lack of theorizing and linking of conceptual with empirical work in media diversity research. Based on this, we develop a framework on how to move forward: Regarding conceptualization, we call for focusing on different places in the journalistic information chain instead of the classical exposure-supply distinction. Methodologically, automated approaches (e.g., analyzing digital traces) and qualitative approaches (e.g., capturing perceptions of diversity) should receive more attention. For analysis, matters of balance and disparity need to be stressed more, especially discussing possible limits to diversity. Overall, research into media diversity thus needs to be addressed in interdisciplinary collaboration." (Abstract)