diff --git a/guides/source/api_documentation_guidelines.md b/guides/source/api_documentation_guidelines.md
index 8e9833c381526b5fa9a2cc124a6ad84dcbcb07e0..a4feff798df9538d657264f2682d2322381845d9 100644
--- a/guides/source/api_documentation_guidelines.md
+++ b/guides/source/api_documentation_guidelines.md
@@ -87,7 +87,7 @@ Please use American English (*color*, *center*, *modularize*, etc). See [a list
 Comma
 -------
 
-Please use Oxford comma (*red, white, and blue* style). See [the detail of Oxford comma](http://en.wikipedia.org/wiki/Serial_comma).
+Please use the Oxford comma (*red, white, and blue* style). See [the detail of Oxford comma](http://en.wikipedia.org/wiki/Serial_comma).
 
 Example Code
 ------------