This dataset contains one instance of the information used in searching and screening peer-reviewed literature to identify references to be used in EPA's Integrated Science Assessments (ISAs). It is comprised of six subsets, three for each of two ISAs for Ozone (2013 and 2020). The subsets are reference metadata, which contains all metadata for references found through searches and references cited in the respective ISA, Citation context, which contains the text of paragraph of the ISA where each reference was cited, and the semantic map, which provides the outline of the ISA in a hierarchical table of chapters, sections and subsections. See the Supporting documents for a more detailed description.