@inproceedings{vonHippel:2009K8, author = "von Hippel, Georg", title = "{Perturbative improvement with HISQ fermions: the gluon action at $O(N_f \alpha_s a^2)$ }", doi = "10.22323/1.066.0046", booktitle = "Proceedings of The XXVI International Symposium on Lattice Field Theory {\textemdash} PoS(LATTICE 2008)", year = 2009, volume = "066", pages = "046" }