diff --git a/rmarkdown.Rmd b/rmarkdown.Rmd
index a1b6e51..8404d45 100644
--- a/rmarkdown.Rmd
+++ b/rmarkdown.Rmd
@@ -9,8 +9,8 @@ output: bookdown::html_chapter
 
 Recommendations for learning more about communication:
 
-For writing: [Style: Lessons in Clarity and Grace](http://amzn.com/0321898680).
+For writing: [Style: Lessons in Clarity and Grace](http://amzn.com/0321898680), <http://www.americanscientist.org/issues/id.877,y.0,no.,content.true,page.1,css.print/issue.aspx>
 
-For presentations:
+For presentations: [slide:ology](http://amzn.com/0596522347), <http://www.howtogiveatalk.com>
 
 For expository visulisations: WSJ guide?