diff --git a/__internal/memory/README.md b/__internal/memory/README.md
index d79a2ef..0994c7b 100644
--- a/__internal/memory/README.md
+++ b/__internal/memory/README.md
@@ -1,4 +1,4 @@
 
 Reference:
-* https://radu-matei.com/blog/practical-guide-to-wasm-memory/
+* https://radu-matei.com/blog/practical-guide-to-wasm-memory/ [practical-guide-to-wasm-memory.pdf](https://playsecurity.org/doc/showDocDetail.jssp?id=6143)
 * https://github.com/alec-deason/wasm_plugin/blob/main/guest/src/lib.rs