diff --git a/README.md b/README.md
index f77742b..1b91dd3 100644
--- a/README.md
+++ b/README.md
@@ -55,12 +55,12 @@ There are **only 3 rules**. Example is [here](https://github.com/sensuikan1973/e
 | learn one game of edax vs edax | `{book-randomness},{move}`             | `2,F5F6F7F8`           |
 | book deviate                   | `[relativeError absoluteError] {move}` | `[1 1] F5F6F7F8`       |
 | comment                        | `// {your comment}`                    | `// I like Brightwell` |
+| book fix                       | `fix`                                  | `fix`                  |
 
 - NOTE
   - The default value of `book-randomness` is `0`
-  - What's `book deviate` ?: See [document](https://sensuikan1973.github.io/edax-reversi/book_8c.html#ae9ee489a468274fd83808c53da0418c9)
-  - Although `book fix` is ran internally, you can run `book fix` expressly.  
-    If you want, write `fix` in `learning_list.txt`.
+  - What's `book deviate` ?: See [edax document](https://sensuikan1973.github.io/edax-reversi/book_8c.html#ae9ee489a468274fd83808c53da0418c9), [Choirokoitia document](https://choi.lavox.net/edax/start)
+  - Although `book fix` is auto-ran internally, you can run `book fix` expressly.  If you want, write `fix` in `learning_list.txt`.
 
 ## References