diff --git a/src/util/reverse.scad b/src/util/reverse.scad
index 2e32df91..d2696b02 100644
--- a/src/util/reverse.scad
+++ b/src/util/reverse.scad
@@ -1,3 +1,13 @@
+/**
+* reverse.scad
+*
+* @copyright Justin Lin, 2017
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib2-reverse.html
+*
+**/ 
+
 include <util/__comm__/__reverse.scad>;
 
 function reverse(lt) = __reverse(lt);
\ No newline at end of file
diff --git a/src/util/slice.scad b/src/util/slice.scad
index 6fae13fe..0eb9c0c5 100644
--- a/src/util/slice.scad
+++ b/src/util/slice.scad
@@ -1,3 +1,13 @@
+/**
+* slice.scad
+*
+* @copyright Justin Lin, 2017
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib2-slice.html
+*
+**/ 
+
 function slice(lt, begin, end) = 
     let(ed = is_undef(end) ? len(lt) : end)
     [for(i = begin; i < ed; i = i + 1) lt[i]];
diff --git a/src/util/sort.scad b/src/util/sort.scad
index 33946db9..0c51290a 100644
--- a/src/util/sort.scad
+++ b/src/util/sort.scad
@@ -1,3 +1,13 @@
+/**
+* sort.scad
+*
+* @copyright Justin Lin, 2017
+* @license https://opensource.org/licenses/lgpl-3.0.html
+*
+* @see https://openhome.cc/eGossip/OpenSCAD/lib2-sort.html
+*
+**/ 
+
 function _sort(lt, i) = 
     let(leng = len(lt))
     leng <= 1 ? lt :