This is the final version. Available on open access from Taylor & Francis via the DOI in this recordIn this article we map and explain the sources of knowledge cited on 85 Brexit impact appraisals, 46 of which were formal impact assessments ordered and published by the European Parliament and 39 ‘sectoral reports’ ordered by the UK Government and released by the House of Commons Exiting the EU Committee. All reports were published between the day after the UK referendum and the year after the start of the UK-EU negotiations. We conducted a citation analysis of 3537 references and tested author push and policy sector pull hypotheses with non-parametric tests. Our findings highlight the epistemic function of the professional referent groups to which authors belong. Authors tend to generate information and cite sources that are congruent with their ‘home group’ in the departmental unit where they work, or their larger professional group, even in urgent high-salient risk situations like Brexit. Differences between policy sectors do not strongly matter
