@inproceedings{eCosta:2009yf,
  author = "e Costa, Sandro Silva",
  title = "{Scalar fields, density perturbations and the Chaplygin gas}",
  doi = "10.22323/1.081.0069",
  booktitle = "Proceedings of 5th International School on Field Theory and Gravitation {\textemdash} PoS(ISFTG)",
  year = 2009,
  volume = "081",
  pages = "069"
}