@Article{Norrish:HOSC:2006,
  author =       {Michael Norrish},
  title =        {Mechanising $\lambda$-Calculus Using a Classical First Order
                  Theory of Terms with Permutations},
  journal =      {Higher-Order and Symbolic Computation},
  year =         2006,
  volume =       19,
  pages =        {169--195},
  doi =          {10.1007/s10990-006-8745-7}
}