diff --git a/src/Plane.cpp b/src/Plane.cpp
index b4c88b4..2c18def 100644
--- a/src/Plane.cpp
+++ b/src/Plane.cpp
@@ -4,8 +4,7 @@
 bool Plane::intersect(
     const Ray & ray, const double min_t, double & t, Eigen::Vector3d & n) const
 {
-    /**
-     * Based on
+    /* Based on
      * Computer Graphics, Chapter 4. Ray Tracing
      * Peter Lamber & Glenn Van Wallendael
      */
diff --git a/src/Sphere.cpp b/src/Sphere.cpp
index 19e131d..3ffc9c0 100644
--- a/src/Sphere.cpp
+++ b/src/Sphere.cpp
@@ -3,8 +3,7 @@
 bool Sphere::intersect(
     const Ray & ray, const double min_t, double & t, Eigen::Vector3d & n) const
 {
-    /**
-     * Based on
+    /* Based on
      * Fundamentals in Computer Graphics - Fourth Edition, Chapter 4.4.1. Ray-Sphere Intersection.
      * Steve Marschner & Peter Shirley
      */
diff --git a/src/viewing_ray.cpp b/src/viewing_ray.cpp
index 2a7ae6d..4a7218a 100644
--- a/src/viewing_ray.cpp
+++ b/src/viewing_ray.cpp
@@ -8,8 +8,7 @@ void viewing_ray(
     const int height,
     Ray & ray)
 {
-    /**
-     * Based on
+    /* Based on
      * Fundamentals in Computer Graphics - Fourth Edition, Chapter 4.3.2 Perspective views.
      * Steve Marschner & Peter Shirley
      */