Master integrals for four-loop massless form factors Roman N. Lee, Andreas von Manteuffel, Robert M. Schabinger, Alexander V. Smirnov, Vladimir A. Smirnov and Matthias Steinhauser Eur. Phys. J. C, 83 11 (2023) 1041 Published online: 16 November 2023 DOI: 10.1140/epjc/s10052-023-12179-2