deletions | additions       diff --git a/bibliography/biblio.bib b/bibliography/biblio.bib  index a47b882..5539f15 100644  --- a/bibliography/biblio.bib  +++ b/bibliography/biblio.bib 
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@article{undefined,  title = {{Quantitative seismology}},  author = {Aki, Keiiti and Richards, Paul G},  year = {1980},  publisher = {Freeman San Francisco}, {2002},  }