1. Berestovskii V. N., “Homogeneous spaces with intrinsic metric,” Soviet Math. Dokl., vol. 38, no. 2, 60–63 (1989).
2. Pontryagin L. S., Boltyanskii V. G., Gamkrelidze R. V., and Mishchenko E. F., The Mathematical Theory of Optimal Processes, John Wiley and Sons, New York and London (1962).
3. Milnor J., “Curvatures of left invariant metrics on Lie groups,” Adv. Math., vol. 21, no. 3, 293–329 (1976).
4. Berestovskii V. N., “Homogeneous manifolds with intrinsic metric. I,” Sib. Math. J., vol. 29, no. 6, 887–897 (1988).
5. Berestovskii V. N., “Curvatures of homogeneous sub-Riemannian manifolds,” Eur. J. Math., vol. 3, 788–807 (2017).