deletions | additions       diff --git a/bibliography/biblio.bib b/bibliography/biblio.bib  index 3a83a57..3ad832a 100644  --- a/bibliography/biblio.bib  +++ b/bibliography/biblio.bib 
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URL = {http://bioscience.oxfordjournals.org/content/56/12/987.abstract},   eprint = {http://bioscience.oxfordjournals.org/content/56/12/987.full.pdf+html},   journal = {BioScience}   }  @article{Costanza_1997,  doi = {http://dx.doi.org/10.1038/387253a0},  url = {http://www.esd.ornl.gov/benefits_conference/nature_paper.pdf},  year = {1997},  publisher = {Nature},  volume = {387},  number = {6630},  pages = {253-260},  author = {R. Costanza and R. d'Arge and R. de Groot and S. Farber and M. Grasso and B. Hannon and K. Limburg and S. Naeem and R. O'Neil and J. Paruelo and R. Raskin and P. Sutton and M. van den Belt},  title = {{The value of the world's ecosystem services and natural capital}},  journal = {Nature},  }