diff --git a/user/src/bin/stackless_coroutine.rs b/user/src/bin/stackless_coroutine.rs
index 39200e50..43aeb2de 100644
--- a/user/src/bin/stackless_coroutine.rs
+++ b/user/src/bin/stackless_coroutine.rs
@@ -1,3 +1,5 @@
+// https://blog.aloni.org/posts/a-stack-less-rust-coroutine-100-loc/
+// https://github.com/chyyuu/example-coroutine-and-thread/tree/stackless-coroutine-x86
 #![no_std]
 #![no_main]