diff --git a/config/en/mkdocs.yaml b/config/en/mkdocs.yaml
index 39e7fb9..868fb4f 100755
--- a/config/en/mkdocs.yaml
+++ b/config/en/mkdocs.yaml
@@ -57,9 +57,12 @@ extra_css:
   - stylesheets/extra.css
 
 extra_javascript:
-  - javascripts/mathjax.js
-  - https://polyfill.io/v3/polyfill.min.js?features=es6
-  - https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js
+  - javascripts/katex.js
+  - https://unpkg.com/katex@0/dist/katex.min.js
+  - https://unpkg.com/katex@0/dist/contrib/auto-render.min.js
+
+extra_css:
+  - https://unpkg.com/katex@0/dist/katex.min.css
 
 nav:
   - 'Welcome': index.md
diff --git a/docs/en/javascripts/katex.js b/docs/en/javascripts/katex.js
new file mode 100644
index 0000000..a5f8713
--- /dev/null
+++ b/docs/en/javascripts/katex.js
@@ -0,0 +1,12 @@
+document$.subscribe(({ body }) => { 
+
+
+    renderMathInElement(body, {
+      delimiters: [
+        { left: "$$",  right: "$$",  display: true },
+        { left: "$",   right: "$",   display: false },
+        { left: "\\(", right: "\\)", display: false },
+        { left: "\\[", right: "\\]", display: true }
+      ],
+    })
+  })
\ No newline at end of file
diff --git a/docs/en/mathematics/linear-algebra/tensors/tensor-formalism.md b/docs/en/mathematics/linear-algebra/tensors/tensor-formalism.md
index 433ccf0..c47e97e 100644
--- a/docs/en/mathematics/linear-algebra/tensors/tensor-formalism.md
+++ b/docs/en/mathematics/linear-algebra/tensors/tensor-formalism.md
@@ -135,7 +135,7 @@ We have from theorem 2 that the outer product of two tensors yields another tens
 
 ## Inner product
 
-> *Definition 5*: a **pseudo inner product** on $V$ is a nondegenerate bilinear mapping $\boldsymbol{g}: V \times V \to \mathbb{K}$ which satisfies
+> *Definition 5*: a **pseudo inner product** on $V$ is a nondegenerate bilinear mapping $\bm{g}: V \times V \to \mathbb{K}$ which satisfies
 >
 > 1. for all $\mathbf{u} \in V \backslash \{\mathbf{0}\} \exists \mathbf{v} \in V: \; \bm{g}(\mathbf{u},\mathbf{v}) \neq 0$,
 > 2. for all $\mathbf{u}, \mathbf{v} \in V: \; \bm{g}(\mathbf{u}, \mathbf{v}) = \overline{\bm{g}}(\mathbf{v}, \mathbf{u})$,