The earliest numerical results on the optical properties of graphene nanoribbons were obtained by Lin and Shyu in 2000. The different selection rules for optical transitions in graphene nanoribbons with armchair and zigzag edges were reported. These results were supplemented by a comparative study of zigzag nanoribbons with single wall armchair carbon nanotubes by Hsu and Reichl in 2007. It was demonstrated that selection rules in zigzag ribbons are different from those in carbon nanotube and the eigenstates in zigzag ribbons can be classified as either symmetric or antisymmetric. Also, it was predicted that edge states should play an important role in the optical absorption of zigzag nanoribbons. Optical transitions between the edge and bulk states should enrich the low-energy region (formula_1 eV) of the absorption spectrum by strong absorption peaks. Analytical derivation of the numerically obtained selection rules was presented in 2011. The selection rule for the incident light polarized longitudinally to the zigzag ribbon axis is that formula_2 is odd, where formula_3 and formula_4 number the energy bands, while for the perpendicular polarization formula_5 is even. Intraband (intersubband) transitions between the conduction (valence) sub-bands are also allowed if formula_5 is even.