diff --git a/src/SUMMARY.md b/src/SUMMARY.md
index bcaef37..ca3b6da 100644
--- a/src/SUMMARY.md
+++ b/src/SUMMARY.md
@@ -8,6 +8,7 @@
     - [Testing](./dev/golang/testing.md)
   - [Elixir](./dev/elixir/main.md)
     - [GenServer](./dev/elixir/genserver.md)
+    - [Dates](./dev/elixir/dates.md)
   - [Rust](./dev/rust/main.md)
     - [serde](./dev/rust/serde.md)
     - [Testing](./dev/rust/testing.md)
diff --git a/src/dev/elixir/dates.md b/src/dev/elixir/dates.md
new file mode 100644
index 0000000..0316889
--- /dev/null
+++ b/src/dev/elixir/dates.md
@@ -0,0 +1,27 @@
+# Dates
+
+When working with dates in Elixir, nerver use "<" or ">", because sometimes, it will not work the way you want
+
+```elixir
+iex(16)> first = Timex.parse!("Tue, 29 Oct 2019 16:00:00 +0000", "%a, %d %b %Y %H:%M:%S %z", :strftime)
+#DateTime<2019-10-29 16:00:00+00:00 GMT Etc/GMT+0>
+iex(17)> second = Timex.parse!("Wed, 06 Nov 2019 23:00:00 +0000", "%a, %d %b %Y %H:%M:%S %z", :strftime)
+#DateTime<2019-11-06 23:00:00+00:00 GMT Etc/GMT+0>
+iex(18)> first < second
+false
+```
+
+# [Timex](https://hexdocs.pm/timex/Timex.html)
+
+For example, with `Timex` comes the `compare` function.
+
+```elixir
+Timex.compare(first, second)
+-1
+```
+
+And return value should be considered as follow :
+
+- -1 : first is before second
+- 0 : first is equal to second
+- 1 : second is before first