 When plotting the index "i" of an edge channel versus the reciprocal of its magnetic flux density 1/"B""i", one obtains a straight line with slope 2 ∙ "e"/("n"∙ "h").Since the electron charge "e" is known and also Planck's constant "h", one can derive the electron density "n" of a sample from this plot.Shubnikov-de Haas oscillations are observed in highly doped Bi2Se3.