@unpublished{Millet-Gilloux,
  author	= {Millet, C. and Gilloux, M.},
  title		= {A Study of the Necessary Knowledge for Explanation in Expert System},
  note		= {C.N.E.T. Lannion A., departement SLC/AIA, Route de Tregastel, B.P. 1, 22301 Lannion, France}
}