1. Ahlfors, L.V.: Bounded analytic functions. Duke Math. J. 14, 1–11 (1947)
2. Ambrosio, L., Fusco, N., Pallara, D.: Functions of bounded variation and free discontinuity problems. Oxford Mathematical Monographs. Oxford University Press, New York (2000)
3. Balogh, Z.M., Tyson, J.T., Warhurst, B.: Sub-Riemannian vs. Euclidean dimension comparison and fractal geometry on Carnot groups. Adv. Math. 220(2), 560–619 (2009)
4. Bonfiglioli, A., Lanconelli, E., Uguzzoni, F.: Stratified Lie groups and potential theory for their sub-Laplacians. Springer Monographs in Mathematics. Springer, Berlin (2007)
5. Capogna, L., Danielli, D., Pauls, S.D., Tyson, J.T.: An introduction to the Heisenberg group and the sub-Riemannian isoperimetric problem, vol. 259 of Progress in Mathematics. Birkhäuser, Basel (2007)