@Article{BarEve81,
  author =       "R. Bar-Yehuda and S. Even",
  title =        "A linear time approximation algorithm for the weighted
                 vertex cover problem",
  journal =      "Journal of Algorithms",
  volume =       "2",
  year =         "1981 ",
  pages =        "198--203",
  abstract =     "A linear time approximation algorithm for the
      weighted set-covering problem is presented.  For the special
      case of the weighted vertex cover problem it produces a
      solution of weight which is at most twice the weight of an
      optimal solution.",
}