Bjorken polarized sum rule and infrared-safe QCD couplings César Ayala, Gorazd Cvetič, Anatoly V. Kotikov and Binur G. Shaikhatdenov Eur. Phys. J. C, 78 12 (2018) 1002 Published online: 10 December 2018 DOI: 10.1140/epjc/s10052-018-6490-9