@article{
  author = {khorramizadeh, S. M., Esfandyaran, D.},
  title = {Orienteering Problem with Variable Profits, Fractional Objective Function and Demand on Arcs},
  journal = {Journal of New Researches in Mathematics},
  year = {1970},
  volume = {5},
  number = {3},
  pages = {19-30},
  doi = {}
}