  The high-order harmonic generation in finite topological nanoribbons is
investigated using a tight-binding description. The ribbons consist of hexagons
and are almost one-dimensional. Two edge states emerge at the short edges of
the ribbon after a gap closure between valence and conduction band, indicating
a topological phase transition. The energies of those edge states as functions
of the tight-binding parameters display crossings and avoided crossings, which
influence the high-harmonic spectra.
