@article{CTT100588771,
  author = {Ryoso Hamane and Toshiya Itoh and Kouhei Tomita},
  title = {Approximation Algorithms for the Highway Problem under the Coupon Model},
  journal = {IEICE Trans. on Fundamentals},
  year = 2009,
}

@article{CTT100570498,
  author = {Ryoso Hamane and Toshiya Itoh and Kouhei Tomita},
  title = {Approximation Preserving Reductions among Item Pricing Problems},
  journal = {IEIC Transactions on Information and Systems},
  year = 2009,
}

@article{CTT100549263,
  author = {Toshiya Itoh and Ryoso Hamane},
  title = {Improved Approximation Allgorithms for Item Pricing with Bounded Degree and Valuation},
  journal = {IEICE Trans. on Information and Systems},
  year = 2008,
}

@misc{CTT100547501,
  author = {Ryoso Hamane and Toshiya Itoh and Kouhei Tomita},
  title = {Approximation Algorithms for the Highway Problem under the Coupon Model},
  year = 2007,
}