  The field emission of crystalline AAA graphite is studied within a simple
analytical approach with account of the exact dispersion relation near the
Fermi level. The emission current is calculated for two crystal orientations
with respect to the applied electric field. It is found that the exponent of
the Fowler-Nordheim equation remains the same while the preexponential factor
is markedly modified. For both field directions, the linear field dependence is
found in weak fields and the standard quadratic Fowler-Nordheim behavior takes
place in strong fields. A strong dependence of the emission current from the
interlayer distance is observed. As an illustration of the method the known
case of a single-walled carbon nanotube is considered.
