Higher-order regularity in local and nonlocal quantum gravity Nicolò Burzillà, Breno L. Giacchini, Tibério de Paula Netto and Leonardo Modesto Eur. Phys. J. C, 81 5 (2021) 462 Published online: 26 May 2021 DOI: 10.1140/epjc/s10052-021-09238-x