diff --git a/03-bootsector-memory/README.md b/03-bootsector-memory/README.md
index c8d9b60..61ff534 100644
--- a/03-bootsector-memory/README.md
+++ b/03-bootsector-memory/README.md
@@ -3,7 +3,7 @@
 **Goal: Learn how the computer memory is organized**
 
 Please open page 14 [of this document](
-http://www.cs.bham.ac.uk/~exr/lectures/opsys/10_11/lectures/os-dev.pdf)<sup>1</sup>
+https://web.archive.org/web/20131205064209/http://www.cs.bham.ac.uk/~exr/lectures/opsys/10_11/lectures/os-dev.pdf)<sup>1</sup>
 and look at the figure with the memory layout.
 
 The only goal of this lesson is to learn where the boot sector is stored
diff --git a/README.md b/README.md
index fad5bad..ce3c226 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,7 @@ but:
 - I'm fed up with people who think that reading an already existing kernel, even if small, is 
 a good idea to learn operating systems.
 
-Inspired by [this document](http://www.cs.bham.ac.uk/~exr/lectures/opsys/10_11/lectures/os-dev.pdf)
+Inspired by [this document](https://web.archive.org/web/20131205064209/http://www.cs.bham.ac.uk/~exr/lectures/opsys/10_11/lectures/os-dev.pdf)
 and the [OSDev wiki](http://wiki.osdev.org/), I'll try to make short step-by-step READMEs and
 code samples for anybody to follow. Honestly, this tutorial is basically the first document but
 split into smaller pieces and without the theory.