@Article{Nic03a,
  author =	{Pierre Nicod{\`e}me},
  title =       {Regexpcount, a symbolic package for counting problems
  on regular expressions and words},
  journal =	{Fundamenta Informaticae},
  year =	2003,
  volume =	56,
  number =      {1-2}
  pages =	{71--88}
}