Quasar clustering at redshift 6 J. Greiner, J. Bolmer, R. M. Yates, M. Habouzit, E. Bañados, P. M. J. Afonso and P. Schady A&A, 654 (2021) A79 Published online: 15 October 2021 DOI: 10.1051/0004-6361/202140790