Y. X. Martins and R. J. Biezuner, “Geometric Regularity Results on $B_{\alpha,\beta}^{k}$-Manifolds, I: Affine Connections”, MFAT, vol. 27, no. 3, pp. 237–257, Sep. 2021, doi: https://doi.org/10.31392/MFAT-npu26_3.2021.05.