add link to reference about undefined behavior
diff --git a/src/what-unsafe-does.md b/src/what-unsafe-does.md
index 67fbe8a..372538e 100644
--- a/src/what-unsafe-does.md
+++ b/src/what-unsafe-does.md
@@ -41,6 +41,9 @@
[`NonNull`] that is null. (Requesting custom invalid values is an unstable
feature, but some stable libstd types, like `NonNull`, make use of it.)
+For a more detailed explanation about "Undefined Bahavior", you may refer to
+[the reference][behavior-considered-undefined].
+
"Producing" a value happens any time a value is assigned, passed to a
function/primitive operation or returned from a function/primitive operation.
@@ -75,6 +78,8 @@
* Abort the program
* Delete the production database
+For more detailed information, you may refer to [the reference][behavior-not-considered-unsafe].
+
However any program that actually manages to do such a thing is *probably*
incorrect. Rust provides lots of tools to make these things rare, but
these problems are considered impractical to categorically prevent.
@@ -84,3 +89,5 @@
[race]: races.html
[target features]: ../reference/attributes/codegen.html#the-target_feature-attribute
[`NonNull`]: ../std/ptr/struct.NonNull.html
+[behavior-considered-undefined]: ../reference/behavior-considered-undefined.html
+[behavior-not-considered-unsafe]: ../reference/behavior-not-considered-unsafe.html
