Figure 1 : Magnetic field dependence (B_{0}= 1 T) of the velocities associated with L_{−1 ;1} and L_{−2 ;2} inter-Landau level excitations shown with, correspondingly, open circles (solid lines) and open stars (dashed lines), as derived from the experiment (data modeling), for G-S, G-hBN, and G-Gr specimens. Straight lines are theoretical calculations, with ε = 3.9, 7.0, and 12 for G-S, G-hBN, and G-Gr species, respectively, and the corresponding values for ε_{δv} = 1.3, 3.7, and 12.

C. Faugeras et al. Phys. Rev. Lett.** 114**, 126804, (2015)