diff --git a/README.md b/README.md
index 2ebae76..0f75447 100644
--- a/README.md
+++ b/README.md
@@ -820,7 +820,7 @@ and information sources, maintained by thousands of users, developers and author
 all over the world
 (in the *Users* column number of contributors/number of stars is shown):
 
-|Cheat sheets           |Repository                                                                          |Users                                                                                                                  |Stars                                                                                                   |Creation Date|
+|Cheat sheets           |Repository                                                                          |C/U*                                                                                                                  |Stars                                                                                                   |Creation Date|
 |-----------------------|------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------|-------------|
 |UNIX/Linux, programming|[cheat.sheets](https://github.com/chubin/cheat.sheets)                              |![](https://img.shields.io/github/contributors-anon/chubin/cheat.sheets?label=%F0%9F%91%A5&labelColor=white)           |![](https://img.shields.io/github/stars/chubin/cheat.sheets?label=%E2%AD%90&labelColor=white)           |May 1, 2017  |
 |UNIX/Linux commands    |[tldr-pages/tldr](https://github.com/tldr-pages/tldr)                               |![](https://img.shields.io/github/contributors-anon/tldr-pages/tldr?label=%F0%9F%91%A5&labelColor=white)                           |![](https://img.shields.io/github/stars/tldr-pages/tldr?label=%E2%AD%90&labelColor=white)               |Dec 8, 2013  |
@@ -830,6 +830,8 @@ all over the world
 |Perl                   |[pkrumnis/perl1line.txt](https://github.com/pkrumins/perl1line.txt)                 |![](https://img.shields.io/github/contributors-anon/pkrumins/perl1line.txt?label=%F0%9F%91%A5&labelColor=white)        |![](https://img.shields.io/github/stars/pkrumins/perl1line.txt?label=%E2%AD%90&labelColor=white)        |Nov 4, 2011  |
 |Programming languages  |[StackOverflow](https://stackoverflow.com)                                          |[14M](https://stackexchange.com/leagues/1/alltime/stackoverflow)                                                       |N/A                                                                                                     |Sep 15, 2008 |
 
+<sup>(*) C/U — contributors for GitHub repositories, Users for Stackoverflow</sup>
+
 Pie diagram reflecting cheat sheets sources distribution (by number of cheat sheets on cheat.sh originating from a repository):
 
 ![cheat.sh cheat sheets repositories](http://cheat.sh/files/stat-2017-06-05.png)