From c796cb02bbe506e1c8f5bf51290f6e51306c0011 Mon Sep 17 00:00:00 2001
From: Pavlo Farb <pavlo@cossacklabs.com>
Date: Thu, 26 Oct 2017 19:32:55 +0300
Subject: [PATCH] Update CONTRIBUTING.md

---
 CONTRIBUTING.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 853e870..b6ceb66 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -6,6 +6,8 @@ Your contributions are always welcome! Keep it sane and in line with the general
 
 - Add one link per commit.
 
+- No links to paid resources - only reference materials available for free (or at cost of an e-mail).
+
 - Add one commit per Pull Request.
 
 - Add the link: `- [paper-name](http://example.com/) - A short description ends with a period.` Mentioning authors in description is recommended, if there are too many - mention first 2 and "et al.".