diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 3d7d3ed3d..c7f6908ad 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -3,6 +3,7 @@ Minetest Lua Modding API Reference
 
 * More information at <http://www.minetest.net/>
 * Developer Wiki: <http://dev.minetest.net/>
+* (Unofficial) Minetest Modding Book by rubenwardy: <https://rubenwardy.com/minetest_modding_book/>
 
 Introduction
 ------------