Introduction to Material Nodes - Blender Tutorials
Verge3D for Blender: Shader Nodes Reference — Soft8Soft
Material Basics (nodes) – Blender Knowledgebase
Texture preview in Node Editor in node it self — Right-Click Select
Node-based texturing system design proposal (won't work, this an idea for a GPU based 2D texture authuring node editor) - Blender Development - Developer Forum
New Feature in development: texture nodes - BlenderNation
Translate a texture in Cycles Material node editor? - Blender Stack Exchange
Layered Textures Design — Developer Blog
Shader Editor — Blender Manual
GSOC: Texture Node Editor :Discussion and Suggestion - Summer of Code - Developer Forum