diff --git a/README.md b/README.md
index 314b55a6c3374d3edf36fda45e47b72cdd3e61af..b10c0d0ff0753ef35e1b522fa90b1742e9a3d38b 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,7 @@ This repository contains OpenAPIs descriptions for the interfaces specified in E
 
 ## Online resources
 
+* [Specification document](https://www.etsi.org/deliver/etsi_gs/MEC/001_099/012/01.01.01_60/gs_MEC012v010101p.pdf)
 * [Navigate the API in the browser](https://forge.etsi.org/rep/gitweb.cgi/MEC.GS_012.git/blob/HEAD:/RniAPI.yaml#swagger).
 * [Edit the API online](https://forge.etsi.org/swagger/editor/?url=https://forge.etsi.org/rep/gitweb.cgi/MEC.GS_012.git/blob_plain/HEAD:/RniAPI.yaml).