--- a/debian-apt.rst	Sun May 22 13:25:10 2016 +0300
+++ b/debian-apt.rst	Sun May 22 14:57:22 2016 +0300
@@ -54,10 +54,16 @@
 
   deb http://www.deb-multimedia.org  testing  main non-free
 
+https://wiki.debian.org/SourcesList
+  About ``/etc/apt/sources.list``.
 http://httpredir.debian.org/
   The redirector aims to solve the problem of choosing a Debian mirror.
 https://www.debian.org/security/
   Keeping your Debian system secure.
+https://wiki.debian.org/UnofficialRepositories
+  List of useful unofficial repositories.
+https://www.google.com/linuxrepositories/
+  Links to Google repositories and verification key.
 
 Find nearest mirror
 ===================