deletions | additions       diff --git a/bibliography/biblio.bib b/bibliography/biblio.bib  index a0a4483..217982c 100644  --- a/bibliography/biblio.bib  +++ b/bibliography/biblio.bib 
...
pages = {726-735},  year = {1998}  }  @inproceedings{opt1,  author = {S Chaudhuri},  title = {An Overview of Query Optimization in Relational Systems},  booktitle = {Principles of Database Systems},  address = {Washington, USA}  pages = {34-43},  year = {1998}  }  @inproceedings{opt2,  author = {G Moerkotte, W Scheufele},  title = {Constructing Optimal Bushy Processing Trees for Join Queries is NP-hard},  year = {1996}  }