diff --git a/README.md b/README.md
index 3511dc8..1f72ca0 100644
--- a/README.md
+++ b/README.md
@@ -53,4 +53,8 @@ NurbsSurface::Evaluator nurbsSurfaceEvaluator(
 );
 nurbsSurfaceEvaluator.setRecordTime(true);
 nurbsSurfaceEvaluator.calculate(3, 4);  // 计算时需要传入u、v两个方向的采样数目
-```
\ No newline at end of file
+```
+
+# Primary Reference
++ [Direct Evaluation of NURBS Curves and Surfaces on the GPU - 2007 - Krishnamurthy, Khardekar, Mcmains](https://dl.acm.org/doi/abs/10.1145/1236246.1236293)
++ CUDA C编程权威指南 - 2017 - 程润伟 , Max Grossman , Ty McKercher
\ No newline at end of file