Updated ComputeTangentFrame (markdown)

ComputeTangentFrame.md

@@ -113,7 +113,6 @@ if ( FAILED( ComputeTangentFrame( mesh->indices.data(), nFaces,
 ```
 
 # Further Reading
-Lengyel, Eric. "Computing Tangent Space Basis Vectors for an Arbitrary Mesh". Terathon Software 3D Graphics Library, 2001
-[link](http://www.terathon.com/code/tangent.html)
+Lengyel, Eric. "7.5 Tangent Space", Foundations of Game Engine Development: Volume 2 - Rendering, Terathon Software LLC (2019) [link](http://foundationsofgameenginedev.com/FGED2-sample.pdf)
 
 Mittring, Martin. "Triangle Mesh Tangent Space Calculation". Shader X^4 Advanced Rendering Techniques, 2006