diff --git a/10.brainstorming-innovative-courses/intercambio-curso-electromagnetismo/textbook.en.md b/10.brainstorming-innovative-courses/intercambio-curso-electromagnetismo/textbook.en.md
index 8e82dd014..082f1c25c 100644
--- a/10.brainstorming-innovative-courses/intercambio-curso-electromagnetismo/textbook.en.md
+++ b/10.brainstorming-innovative-courses/intercambio-curso-electromagnetismo/textbook.en.md
@@ -187,21 +187,24 @@ FR : système de coordonnées cartésiennes   <br>
 EN : Cartesian coordinate system
 
 $`\nabla = \vec{e_x}\,\dfrac{\partial}{\partial x}+\vec{e_y}\,\dfrac{\partial}{\partial y}
-+\vec{e_z}\,\dfrac{\partial}{\partial z} `$   <br>
++\vec{e_z}\,\dfrac{\partial}{\partial z} `$  
+, or 
+$`\nabla = \overrightarrow{e_x}\,\dfrac{\partial}{\partial x}+\overrightarrow{e_y}\,\dfrac{\partial}{\partial y}
++\overrightarrow{e_z}\,\dfrac{\partial}{\partial z} `$ <br>
 ES : operador nabla   <br>
 FR : opérateur nabla   <br>
 EN : nabla operator
 
-$`\overrightarrow{grad}\;f=\nabla\;f`$, $`\overrightarrow{\nabla}\;f``$ better, no?   <br>
+$`\overrightarrow{grad}\;f=\nabla\;f`$, $`\overrightarrow{\nabla}\;f`$ better, no?   <br>
 ES : gradiente   <br>
 FR : gradient   <br>
 EN : gradient
 
-$`div \vec{U}= \nabla \cdot \vec{U}`$ , $`div \vec{U}= \vec{\nabla} \cdot \vec{U}`$    <br>
+$`div\;\vec{U}= \nabla \cdot \vec{U}`$ , $`div\;\vec{U}= \vec{\nabla} \cdot \vec{U}`$    <br>
 ES : divergencia   <br>
 FR : divergence   <br>
 EN : divergence   <br>
-$div \vec{U} = \lim_{V \to 0} \; \dfarc{1}{V} \; \oiint_{S\leftrightarrow V} \vec{U} \cdot \vec{dS}`$ 
+$`div\;\vec{U}=\lim_{V\leftrightarrow0}\;\dfrac{1}{V}\;\oiint_{S\leftrightarrow V}\vec{U}\cdot\vec{dS}`$ 
 
 ES : escalar = número real o complexo + unidad de medida?   <br>
 FR : scalaire = nombre réel ou complexe + unité de mesure   <br>