deletions | additions       diff --git a/bibliography/biblio.bib b/bibliography/biblio.bib  index f55cd91..70d511c 100644  --- a/bibliography/biblio.bib  +++ b/bibliography/biblio.bib 
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@Essential University Physics{Wolfson, @BOOK{Wolfson,  Richard Wolfson,Essential University Physics,Addison-Wesley,2007[,2]}