@article{
  author = {Pirmoradian, Nader, Shamsnia, Seyyed Amir, Boustani, Fardin, Shahrokhnia, Mohammad Ali},
  title = {ٍEvaluation of drought return period using standardized precipitation index (SPI) in Fars province, Iran},
  journal = {Agroecology Journal},
  year = {2009},
  volume = {4},
  number = {4},
  pages = {7-21},
  doi = {}
}