@Unpublished{     LibkinMuchnik,
  Author        = "Libkin, Leonid and Muchnik, Ilya",
  date-added    = "2013-04-05 07:21:25 +0000",
  date-modified = "2013-04-05 07:21:59 +0000",
  Keywords      = "lattice theory",
  Title         = "The Lattice of Subsemilattices of a Semilattice",
  Year          = "1994",
  File          = "The Lattice of Subsemilattices of a Semilattice - Libkin, Muchnik (0) (0) - a - a - r.pdf",
  file-2        = "The Lattice of Subsemilattices of a Semilattice - Libkin, Muchnik (1) (0) - a - a - r.pdf"
}

@Unpublished{ LibkinMuchnik, Author = "Libkin, Leonid and Muchnik, Ilya", date-added = "2013-04-05 07:21:25 +0000", date-modified = "2013-04-05 07:21:59 +0000", Keywords = "lattice theory", Title = "The Lattice of Subsemilattices of a Semilattice", Year = "1994", File = "The Lattice of Subsemilattices of a Semilattice - Libkin, Muchnik (0) (0) - a - a - r.pdf", file-2 = "The Lattice of Subsemilattices of a Semilattice - Libkin, Muchnik (1) (0) - a - a - r.pdf" }