diff --git a/materialy b/materialy
index 4bca484..b74e166 100644
--- a/materialy
+++ b/materialy
@@ -11,5 +11,7 @@ https://learnopengl.com/Guest-Articles/2022/Phys.-Based-Bloom
 Perlin noise:
 
 https://rtouti.github.io/graphics/perlin-noise-algorithm
+https://adrianb.io/2014/08/09/perlinnoise.html
+https://pl.khanacademy.org/computing/computer-programming/programming-natural-simulations/programming-noise/a/perlin-noise
 
 Atmospheric Scattering:
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