relating to issue #256 (#285)

Author: akshayparopkari

_episodes/03-working-with-files.md

@@ -194,6 +194,8 @@ $ !260
 
 Type `!` (exclamation point) and then the number of the command from your history.
 You will be glad you learned this when you need to re-run very complicated commands.
+For more information on advanced usage of `history`, read section 9.3 of
+[Bash manual](https://www.gnu.org/software/bash/manual/html_node/index.html).
 
 > ## Exercise
 > Find the line number in your history for the command that listed all the .sh

reference.md

@@ -209,7 +209,8 @@ wildcard
 * [Unix cheat sheet](https://files.fosswire.com/2007/08/fwunixref.pdf)
 
 ### Manuals
-* [GNU manuals](http://www.gnu.org/manual/manual.html)
+* [GNU BASH reference](https://www.gnu.org/software/bash/manual/html_node/index.html)
+* [GNU manual](http://www.gnu.org/manual/manual.html)
 * [Core GNU utilities](http://www.gnu.org/software/coreutils/manual/coreutils.html)
 
 ### FASTQ files