@article{villalba2011estimating,
  title = {Estimating GHG emissions of marine ports—the case of Barcelona}
  author = {Villalba, Gara; Gemechu, Eskinder Demisse},
  journal = {Energy Policy},
  url = {http://www.sciencedirect.com/science/article/pii/S030142151000889X},
  doi = {10.1016/j.enpol.2010.12.008},
  year = {2011}
}