diff --git a/documentation/en/30_Contributor_doc/bookmarks-for-potential-features.md b/documentation/en/30_Contributor_doc/bookmarks-for-potential-features.md
index 6e8f746f..cdc97267 100644
--- a/documentation/en/30_Contributor_doc/bookmarks-for-potential-features.md
+++ b/documentation/en/30_Contributor_doc/bookmarks-for-potential-features.md
@@ -6,8 +6,9 @@
 * https://github.com/moby/moby/blob/master/CONTRIBUTING.md
 
 ## UI / UX examples
-* [Accessible Color Spaces](https://github.com/KevinGutowski/KevinGutowski.github.io)
-    * src: http://kevingutowski.github.io/color.html
+* https://www.colorbox.io/ (color tool to produce color sets)
+* [Accessible Color Spaces](http://kevingutowski.github.io/color.html)
+    * src: https://github.com/KevinGutowski/KevinGutowski.github.io
 
 ## schema.org
 - https://www.w3.org/wiki/WebSchemas/Accessibility
diff --git a/documentation/en/90_Resources/Other-contrast-tools.md b/documentation/en/90_Resources/Other-contrast-tools.md
index 96866eec..05fec508 100644
--- a/documentation/en/90_Resources/Other-contrast-tools.md
+++ b/documentation/en/90_Resources/Other-contrast-tools.md
@@ -29,8 +29,8 @@
     * src: https://github.com/donnieberg/accessible-color-palette/
 * https://ryanhemphill.github.io/contrast-colorblind-colorpicker/
     * src: https://github.com/ryanhemphill/contrast-colorblind-colorpicker
-* [Accessible Color Spaces](https://github.com/KevinGutowski/KevinGutowski.github.io)
-    * src: http://kevingutowski.github.io/color.html
+* [Accessible Color Spaces](http://kevingutowski.github.io/color.html)
+    * src: https://github.com/KevinGutowski/KevinGutowski.github.io
 * https://github.com/johnotander/get-contrast
 * http://www.randoma11y.com/
 * https://www.joedolson.com/tools/color-contrast-tester.php
@@ -77,4 +77,18 @@
 * http://www.getstark.co/
     * https://github.com/stark-contrast/stark-sketch-plugin
 
+### no tested tools
+* https://chrome.google.com/webstore/detail/i-want-to-see-like-the-co/jebeedfnielkcjlcokhiobodkjjpbjia
+* https://chrome.google.com/webstore/detail/colorblinding/dgbgleaofjainknadoffbjkclicbbgaa
+* https://chrome.google.com/webstore/detail/spectrum/ofclemegkcmilinpcimpjkfhjfgmhieb
+* https://chrome.google.com/webstore/detail/colorblind-dalton-for-goo/afcafnelafcgjinkaeohkalmfececool
+* https://michelf.ca/projects/sim-daltonism/ color blindness simulator for Mac and iOS
+  * https://github.com/michelf/sim-daltonism
+* http://colororacle.org/  color blindness simulator for Linux, Mac and Windows)
+  * https://github.com/nvkelso/color-oracle-java
+* http://www.rgblind.se/ (open-source)
+  * https://github.com/interaktivarum/rgblind (web toolkit)
+  * http://www.rgblind.se/url (online color blindness simulator for URLs)
+
+
 
diff --git a/documentation/en/90_Resources/Understanding-color-blindness.md b/documentation/en/90_Resources/Understanding-color-blindness.md
index c4d0cb14..1273bf29 100644
--- a/documentation/en/90_Resources/Understanding-color-blindness.md
+++ b/documentation/en/90_Resources/Understanding-color-blindness.md
@@ -1,8 +1,13 @@
+# Color blindness
 
-# Understanding color blindness
+## Understanding color blindness
 
 - [Color blindness from Wikipedia](https://en.wikipedia.org/wiki/Color_blindness)
 "Color blindness, also known as color vision deficiency, is the decreased ability to see color or differences in color."
+- [Types of Colour Blindness](http://www.colourblindawareness.org/colour-blindness/types-of-colour-blindness/)
+"The 8% of colour blind men can be divided approximately into 1% deuteranopes, 1% protanopes, 1% protanomalous and 5% deuteranomalous."
+
+## Designing for Colour Blindness
 - [Designing for Colour Blindness](https://sidigital.co/articles/designing-for-colour-blindness/) (Si digital / 2016)
 "It’s estimated that around 1 in 12 men (8%) and 1 in 200 women have some form of colour blindness."
 - [Colour Accessibility](https://24ways.org/2012/colour-accessibility) (24ways.org / 2012)
diff --git a/documentation/en/Other-contrast-tools.md b/documentation/en/Other-contrast-tools.md
new file mode 120000
index 00000000..a85cf662
--- /dev/null
+++ b/documentation/en/Other-contrast-tools.md
@@ -0,0 +1 @@
+90_Resources/Other-contrast-tools.md
\ No newline at end of file