Add more interesting links

@@ -58,3 +58,22 @@ manually. Finally you have to tell rustc to use lld as linker via this
 environment variable:
 
     export RUSTFLAGS="-C linker=lld"
+
+## Traits when, how & why
+
+A slightly old but still worthwhile post about rusts standard traits.
+
+[About traits](https://llogiq.github.io/2015/07/30/traits.html)
+
+# Side note... 3d math
+[3d math primer](https://www.3dgep.com/3d-math-primer-for-game-programmers-vector-operations/)
+[basic 3d math](https://matrix44.net/cms/notes/opengl-3d-graphics/basic-3d-math-vectors/)
+[vector calculator](https://www.mathportal.org/calculators/matrices-calculators/vector-calculator.php)
+[3d vector mathematics](https://vvvv.org/documentation/3d-vector-mathematics)
+[sin appr. with fractions](https://dsp.stackexchange.com/questions/46629/finding-polynomial-approximations-of-a-sine-wave)
+
+# more math...
+
+A whole lot of interesting stuff about continued fractions:
+[continues fractions](http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/cfINTRO.html)
+