diff --git a/html/02_Proofs_with_Structure.html b/html/02_Proofs_with_Structure.html
index 03f76d8c..80c470b9 100644
--- a/html/02_Proofs_with_Structure.html
+++ b/html/02_Proofs_with_Structure.html
@@ -1710,7 +1710,7 @@ <h3><span class="section-number">2.5.9. </span>Exercises<a class="headerlink" hr
 <dl class="footnote brackets">
 <dt class="label" id="id39"><span class="brackets"><a class="fn-backref" href="#id37">3</a></span></dt>
 <dd><p>Example adapted from Hammack,
-<a class="reference external" href="https://www.people.vcu.edu/~rhammack/BookOfProof/">Book of Proof</a>, Section 7.3.</p>
+<a class="reference external" href="https://archive.org/details/book-of-proof-3rd-edition-2018-richard-hammack">Book of Proof</a>, Section 7.3.</p>
 </dd>
 </dl>
 </section>
diff --git a/html/03_Parity_and_Divisibility.html b/html/03_Parity_and_Divisibility.html
index 87d7c011..83eaa099 100644
--- a/html/03_Parity_and_Divisibility.html
+++ b/html/03_Parity_and_Divisibility.html
@@ -502,7 +502,7 @@ <h3><span class="section-number">3.1.10. </span>Exercises<a class="headerlink" h
 <dl class="footnote brackets">
 <dt class="label" id="id11"><span class="brackets"><a class="fn-backref" href="#id10">1</a></span></dt>
 <dd><p>Exercise taken from Hammack,
-<a class="reference external" href="https://www.people.vcu.edu/~rhammack/BookOfProof/">Book of Proof</a>, Chapter 9.</p>
+<a class="reference external" href="https://archive.org/details/book-of-proof-3rd-edition-2018-richard-hammack">Book of Proof</a>, Chapter 9.</p>
 </dd>
 </dl>
 </section>
diff --git a/html/06_Induction.html b/html/06_Induction.html
index 5abbfc38..32d31be8 100644
--- a/html/06_Induction.html
+++ b/html/06_Induction.html
@@ -1382,7 +1382,7 @@ <h3><span class="section-number">6.3.6. </span>Exercises<a class="headerlink" hr
 <dl class="footnote brackets">
 <dt class="label" id="id22"><span class="brackets"><a class="fn-backref" href="#id19">1</a></span></dt>
 <dd><p>Example adapted from Hammack,
-<a class="reference external" href="https://www.people.vcu.edu/~rhammack/BookOfProof/">Book of Proof</a>, Section 10.5.</p>
+<a class="reference external" href="https://archive.org/details/book-of-proof-3rd-edition-2018-richard-hammack">Book of Proof</a>, Section 10.5.</p>
 </dd>
 </dl>
 </section>