diff --git a/content/articles/course-html5/codificacion.md b/content/articles/course-html5/codificacion.md
index a48dc1d..01faddb 100644
--- a/content/articles/course-html5/codificacion.md
+++ b/content/articles/course-html5/codificacion.md
@@ -22,4 +22,7 @@ Código de ayuda:
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 ~~~~
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
+
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/etiqueta-a.md b/content/articles/course-html5/etiqueta-a.md
index 0c399e2..00eeb1c 100644
--- a/content/articles/course-html5/etiqueta-a.md
+++ b/content/articles/course-html5/etiqueta-a.md
@@ -16,7 +16,9 @@ Title: Etiqueta a
 
 <details markdown="span">
 <summary>Mostrar Más</summary>
-Más sobre la etiqueta `<a>` en la [w3schools][w3school]{:target="_blank" rel="noopener noreferrer"}
+<p class="mb-0">Más sobre la etiqueta `<a>` en la [w3schools][w3school]{:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
 
 [w3school]: https://www.w3schools.com/tags/tag_a.asp
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/etiqueta-article.md b/content/articles/course-html5/etiqueta-article.md
index 4f6d5e7..0e7fa5a 100644
--- a/content/articles/course-html5/etiqueta-article.md
+++ b/content/articles/course-html5/etiqueta-article.md
@@ -17,6 +17,8 @@ Title: Etiqueta article
 <details markdown="span">
 <summary>Mostrar Más</summary>
 <p class="mb-0">Más sobre la etiqueta `<article>` en la [w3schools][w3-article]{:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
 
 [w3-article]: https://www.w3schools.com/tags/tag_article.asp
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/etiqueta-aside.md b/content/articles/course-html5/etiqueta-aside.md
index 7777e0a..85dee44 100644
--- a/content/articles/course-html5/etiqueta-aside.md
+++ b/content/articles/course-html5/etiqueta-aside.md
@@ -17,6 +17,8 @@ Title: Etiqueta aside
 <details markdown="span">
 <summary>Mostrar Más</summary>
 <p class="mb-0">Más sobre la etiqueta `<aside>` en la [w3schools][w3-aside]{:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
 
 [w3-aside]: https://www.w3schools.com/tags/tag_aside.asp
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/etiqueta-nav-ul-ol-li.md b/content/articles/course-html5/etiqueta-nav-ul-ol-li.md
index 0c95115..1180444 100644
--- a/content/articles/course-html5/etiqueta-nav-ul-ol-li.md
+++ b/content/articles/course-html5/etiqueta-nav-ul-ol-li.md
@@ -20,9 +20,11 @@ Title: Etiqueta nav ul ol li
 <p class="mb-0">Más sobre la etiqueta `<ul>` en la [w3schools][w3-ul]{:target="_blank" rel="noopener noreferrer"}</p>
 <p class="mb-0">Más sobre la etiqueta `<ol>` en la [w3schools][w3-ol]{:target="_blank" rel="noopener noreferrer"}</p>
 <p class="mb-0">Más sobre la etiqueta `<li>` en la [w3schools][w3-li]{:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
 
 [w3-nav]: https://www.w3schools.com/tags/tag_nav.asp
 [w3-ul]: https://www.w3schools.com/tags/tag_ul.asp
 [w3-ol]: https://www.w3schools.com/tags/tag_ol.asp
 [w3-li]: https://www.w3schools.com/tags/tag_li.asp
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/etiqueta-section.md b/content/articles/course-html5/etiqueta-section.md
index 751e599..073a7ae 100644
--- a/content/articles/course-html5/etiqueta-section.md
+++ b/content/articles/course-html5/etiqueta-section.md
@@ -17,6 +17,8 @@ Title: Etiqueta section
 <details markdown="span">
 <summary>Mostrar Más</summary>
 <p class="mb-0">Más sobre la etiqueta `<section>` en la [w3schools][w3-section]{:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
 
 [w3-section]: https://www.w3schools.com/tags/tag_section.asp
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/etiquetas-p-y-span.md b/content/articles/course-html5/etiquetas-p-y-span.md
index ea8d988..875aaf2 100644
--- a/content/articles/course-html5/etiquetas-p-y-span.md
+++ b/content/articles/course-html5/etiquetas-p-y-span.md
@@ -17,8 +17,10 @@ Title: etiquetas p y span
 <details markdown="span">
 <summary>Mostrar Más</summary>
 <p class="mb-0">Más sobre la etiqueta `<p>` en la [w3schools][w3-p]{:target="_blank" rel="noopener noreferrer"}</p>
-<p>Más sobre la etiqueta `<span>` en la [w3schools][w3-span]{:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">Más sobre la etiqueta `<span>` en la [w3schools][w3-span]{:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
 
 [w3-p]: https://www.w3schools.com/tags/tag_p.asp
 [w3-span]: https://www.w3schools.com/tags/tag_span.asp
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/etiquetas-strong-y-em.md b/content/articles/course-html5/etiquetas-strong-y-em.md
index 05d88a0..1f9ab76 100644
--- a/content/articles/course-html5/etiquetas-strong-y-em.md
+++ b/content/articles/course-html5/etiquetas-strong-y-em.md
@@ -17,8 +17,10 @@ Title: Etiquetas strong y em
 <details markdown="span">
 <summary>Mostrar Más</summary>
 <p class="mb-0">Más sobre la etiqueta `<strong>` en la [w3schools][w3-strong]{:target="_blank" rel="noopener noreferrer"}</p>
-<p>Más sobre la etiqueta `<em>` en la [w3schools][w3-em]{:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">Más sobre la etiqueta `<em>` en la [w3schools][w3-em]{:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
 
 [w3-strong]: https://www.w3schools.com/tags/tag_strong.asp
 [w3-em]: https://www.w3schools.com/tags/tag_em.asp
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/header.md b/content/articles/course-html5/header.md
index 1018151..99c0a29 100644
--- a/content/articles/course-html5/header.md
+++ b/content/articles/course-html5/header.md
@@ -17,7 +17,9 @@ Title: Header
 
 <details markdown="span">
 <summary>Mostrar Más</summary>
-Más información sobre la etiqueta `<header>` en [w3schools][header]{:target="_blank" rel="noopener noreferrer"}.
+<p class="mb-0">Más información sobre la etiqueta `<header>` en [w3schools][header]{:target="_blank" rel="noopener noreferrer"}.</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
 
 [header]: https://www.w3schools.com/tags/tag_header.asp
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/hgroup.md b/content/articles/course-html5/hgroup.md
index 5550140..d029188 100644
--- a/content/articles/course-html5/hgroup.md
+++ b/content/articles/course-html5/hgroup.md
@@ -18,5 +18,9 @@ Title: hgroup
 <summary>Mostrar Más</summary>
 <p class="mb-0">Etiqueta hgroup en desuso.</p>
 <p class="mb-0">Este elemento fue removido de la especificacion HTML5 (W3C), por favor no usar más.</p>
-<p class="mb-0">Referencia: [https://developer.mozilla.org/es/docs/Web/HTML/Elemento/hgroup](https://developer.mozilla.org/es/docs/Web/HTML/Elemento/hgroup){:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">Referencia: [https://developer.mozilla.org/es/docs/Web/HTML/Elemento/hgroup][mozilla-web]{:target="_blank" rel="noopener noreferrer"}</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
+
+[mozilla-web]: https://developer.mozilla.org/es/docs/Web/HTML/Elemento/hgroup
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/intro.md b/content/articles/course-html5/intro.md
index 8685a2a..6fa6e34 100644
--- a/content/articles/course-html5/intro.md
+++ b/content/articles/course-html5/intro.md
@@ -21,9 +21,11 @@ Title: Introducción a HTML5
 <li>[Respositorio oficial][html]{:target="_blank" rel="noopener noreferrer"} de HTML</li>
 <li>[w3schools][w3c]{:target="_blank" rel="noopener noreferrer"}</li>
 <li>[Documentación de la W3C][w3c.org]{:target="_blank" rel="noopener noreferrer"}</li>
+<li>[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</li>
 </ul>
 </details>
 
 [html]: https://github.com/whatwg/html
 [w3c]: https://www.w3schools.com/html/default.asp
 [w3c.org]: https://www.w3.org/TR/html/
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/nuevas-etiquetas.md b/content/articles/course-html5/nuevas-etiquetas.md
index fe49897..3c20f5b 100644
--- a/content/articles/course-html5/nuevas-etiquetas.md
+++ b/content/articles/course-html5/nuevas-etiquetas.md
@@ -16,7 +16,9 @@ Title: Nuevas etiquetas de HTML5
 
 <details markdown="span">
 <summary>Mostrar Más</summary>
-Más información sobre HTML5 en [w3schools][w3c-html5]{:target="_blank" rel="noopener noreferrer"}.
+<p class="mb-0">Más información sobre HTML5 en [w3schools][w3c-html5]{:target="_blank" rel="noopener noreferrer"}.</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
 
 [w3c-html5]: https://www.w3schools.com/html/html5_intro.asp
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/sintaxis-html5.md b/content/articles/course-html5/sintaxis-html5.md
index 7ff626f..abc3ed0 100644
--- a/content/articles/course-html5/sintaxis-html5.md
+++ b/content/articles/course-html5/sintaxis-html5.md
@@ -17,6 +17,7 @@ Title: Sintaxis HTML5
 
 <details markdown="span">
 <summary>Mostrar Más</summary>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 ~~~~{.html}
 <!doctype html>
 <html lang="en">
@@ -29,3 +30,5 @@ Title: Sintaxis HTML5
 </html>
 ~~~~
 </details>
+
+[validator]: https://validator.w3.org/
diff --git a/content/articles/course-html5/titulos.md b/content/articles/course-html5/titulos.md
index 23403ff..b1c7f30 100644
--- a/content/articles/course-html5/titulos.md
+++ b/content/articles/course-html5/titulos.md
@@ -16,7 +16,9 @@ Title: Títulos en HTML5
 
 <details markdown="span">
 <summary>Mostrar más</summary>
-Más información sobre las etiquetas `h` en [w3schools][titles]{:target="_blank" rel="noopener noreferrer"}.
+<p class="mb-0">Más información sobre las etiquetas `h` en [w3schools][titles]{:target="_blank" rel="noopener noreferrer"}.</p>
+<p class="mb-0">[Validador][validator]{:target="_blank" rel="noopener noreferrer"}</p>
 </details>
 
 [titles]: https://www.w3schools.com/hTml/html_headings.asp
+[validator]: https://validator.w3.org/