This @QSS_ISSI paper analyzes the scope, structure, curation, mappings and use of 45 knowledge organization systems (KOS) for academic fields: https://doi.org/10.1162/qss_a_00363 It provides a useful overview of KOS and identifies gaps: The findings show that there is a lack of field-specific KOS in certain areas, and that "there is currently no existing multifield KOS that simultaneously is comprehensive in topic coverage, granular, consistently updated, and openly accessible."