Casual Introduction to Low-Level Graphics Programming by Stephanie Hurlburt
Primer: Shaders by Sven Bergström
A trip through the Graphics Pipeline by Fabian Giesen
Graphics in Plain Language by Baldur Karlsson
GTA V Graphics Study by Adrian Courrèges
Game Art Tricks by Simon Schreibt
GLSL reference
The Book Of Shaders by Patricio Gonzalez Vivo and Jen Lowe
Fragment shader lesson by Matt DesLauriers
Vertex shader lesson by Matt DesLauriers
Shadertoy tutorial by Omar Shehata
Raymarching tutorial by uint9
Articles by Inigo Quilez
Ray Marching and Signed Distance Functions by Jamie Wong
Volumetric Rendering: Raymarching by Alan Zucconi
Raymarching Tutorial pouet.net thread
Raymarching Tutorial by Ruofei Du
SDF Tracing Visualization by panic
Raymarching Tutorial by reinder