diff --git a/docs/en/calculators/hyd_en_charge/lechapt-calmon.md b/docs/en/calculators/hyd_en_charge/lechapt-calmon.md
index ee025f7132a3d3ac30521a69f5be9a834301c629..ba97396cb5fa2362d01c04983159eab37b4bbd6d 100644
--- a/docs/en/calculators/hyd_en_charge/lechapt-calmon.md
+++ b/docs/en/calculators/hyd_en_charge/lechapt-calmon.md
@@ -8,7 +8,7 @@ It allows the calculation of the value of one of the following quantities:
 - Pipe diameter (m)
 - Total head loss (m)
 - Pipe length (m)
-- Singular pressure loss coefficient (m)
+- Singular pressure loss coefficient
 
 The total head loss is the sum of the linear head losses \(J_L\) obtained from the Lechapt and Calmon abacuses and singular \(J_S\) depending on the above coefficient.
 
diff --git a/docs/en/calculators/hyd_en_charge/perte_de_charge.md b/docs/en/calculators/hyd_en_charge/perte_de_charge.md
new file mode 100644
index 0000000000000000000000000000000000000000..3ed9b791fec622b298ce49440f77f31c9b895302
--- /dev/null
+++ b/docs/en/calculators/hyd_en_charge/perte_de_charge.md
@@ -0,0 +1,34 @@
+# Pressure loss
+
+This module computes linear head losses in a circular pipe with the following laws:
+
+- [Lechapt et Calmon](lechapt-calmon.md)
+- [Strickler](strickler.md)
+
+
+The following values can be computed:
+
+- Flow (m<sup>3</sup>/s)
+- Pipe diameter (m)
+- Total pressure loss (m)
+- Pipe length (m)
+- Singular head loss coefficient
+
+The total pressure loss is the sum of linear losses \(J_{lin}\), according to the used law, and singular losses \(J_{loc}\) depending on the above coefficient.
+
+## Singular pressure loss
+
+$$ J_{loc} = K_{loc} \frac{V^2}{2g}$$
+
+Given&nbsp;:
+
+- \(K_{loc}\)&nbsp;: singular head loss coefficient
+- \(V\)&nbsp;: water speed in the pipe (\(V = 4 Q / \pi / D^2\))
+
+## Linear head loss coefficient
+
+$$ K_{lin} = \frac{2g J_{lin}}{V^2} $$
+
+## Darcy head loss coefficient 
+
+$$ f_D = \frac{2g J D}{l_T V^2} $$
diff --git a/docs/en/calculators/hyd_en_charge/strickler.md b/docs/en/calculators/hyd_en_charge/strickler.md
new file mode 100644
index 0000000000000000000000000000000000000000..ea7870e9f1127378070137d44385da317cedb72c
--- /dev/null
+++ b/docs/en/calculators/hyd_en_charge/strickler.md
@@ -0,0 +1,11 @@
+# Strickler formula
+
+This linear head loss law is parameterised by the Stricker coefficient \(K_S\).
+
+The other law parameters are shared with all pressure loss formulas:
+
+- \(Q\) : flow (m<sup>3</sup>/s)
+- \(D\) : pipe diameter (m)
+- \(l_T\) : pipe length (m)
+
+$$J_L=\frac{l_T.Q^2}{(K_S.\pi.D^2/4)^2.(D/4)^{4/3}}$$
diff --git a/docs/fr/calculators/hyd_en_charge/perte_de_charge.md b/docs/fr/calculators/hyd_en_charge/perte_de_charge.md
index 955d4a1b2a67dde51bcb1ce6c79925e48d3767aa..2cc8b986876d9defc3bd85b0716da084e5fd81ee 100644
--- a/docs/fr/calculators/hyd_en_charge/perte_de_charge.md
+++ b/docs/fr/calculators/hyd_en_charge/perte_de_charge.md
@@ -2,8 +2,8 @@
 
 Ce module permet de calculer les pertes de charge dans une conduite circulaire à partir des lois suivantes donnant les pertes de charge linéaires :
 
-- Lechapt et Calmon
-- Strickler
+- [Lechapt et Calmon](lechapt-calmon.md)
+- [Strickler](strickler.md)
 
 Il permet le calcul de la valeur d'une des grandeurs suivantes&nbsp;:
 
diff --git a/e2e/calculator.po.ts b/e2e/calculator.po.ts
index f2b98b2d9f606cd83c86316d46287b1e493676c1..91878a7380ec1d33e7fbedfab4b36a1c6abd00a7 100644
--- a/e2e/calculator.po.ts
+++ b/e2e/calculator.po.ts
@@ -441,4 +441,11 @@ export class CalculatorPage {
             n++;
         }
     }
+
+    /**
+     * get help button related to calculator
+     */
+    getCalculatorHelpButton() {
+        return element(by.css("#help-calc"));
+    }
 }
diff --git a/e2e/documentation.e2e-spec.ts b/e2e/documentation.e2e-spec.ts
new file mode 100644
index 0000000000000000000000000000000000000000..e3a142432e2468131827ff80666eb351322b0a48
--- /dev/null
+++ b/e2e/documentation.e2e-spec.ts
@@ -0,0 +1,68 @@
+import { ListPage } from "./list.po";
+import { CalculatorPage } from "./calculator.po";
+import { Navbar } from "./navbar.po";
+import { browser, by, element } from "protractor";
+import { PreferencesPage } from "./preferences.po";
+
+describe("documentation − ", () => {
+    let listPage: ListPage;
+    let calcPage: CalculatorPage;
+    let prefPage: PreferencesPage;
+    let navbar: Navbar;
+
+    beforeAll(() => {
+        calcPage = new CalculatorPage();
+        prefPage = new PreferencesPage();
+        navbar = new Navbar();
+        listPage = new ListPage();
+
+        // browser.manage().window().setPosition(2000, 30);
+    });
+
+    async function checkMathjaxInHelp(lang: number) {
+        // change language setup
+        await prefPage.navigateTo();
+        await prefPage.changeLanguage(lang);
+        await browser.sleep(200);
+
+        // start page
+        await navbar.clickNewCalculatorButton();
+
+        // open "fish ladder: fall" calculator
+        await listPage.clickMenuEntryForCalcType(12);
+        await browser.sleep(200);
+
+        // click help
+        await calcPage.getCalculatorHelpButton().click();
+        await browser.sleep(200);
+
+        browser.getAllWindowHandles().then(async (handles) => {
+            browser.ignoreSynchronization = true; // deprecated but the only solution to work in the newly opened tab
+
+            // switch to help tab
+            browser.switchTo().window(handles[1]).then(async () => {
+                // check Mathjax element is present
+                expect(element(by.css("mjx-container")).isPresent()).toBe(true);
+            }).then(async () => {
+                // close help tab
+                await browser.close();
+                // switch back to calculator (required to avoid failure of next language test)
+                await browser.switchTo().window(handles[0]);
+                browser.ignoreSynchronization = false;
+            });
+
+            // switch back to calculator (required to avoid failure of next language test)
+            await browser.switchTo().window(handles[0]);
+
+            browser.ignoreSynchronization = false;
+        });
+    }
+
+    it("check Mathjax formula are displayed in calculator French help", async () => {
+        await checkMathjaxInHelp(1); // fr
+    });
+
+    it("check Mathjax formula are displayed in calculator English help", async () => {
+        await checkMathjaxInHelp(0); // en
+    });
+});
diff --git a/scripts/mkdocs-postprocess.js b/scripts/mkdocs-postprocess.js
index 558e8300fe0d45f43ee54530b3a9208fb2725d07..96f0794bb39917ea0db9bb3036a0f1e2e59b02b3 100644
--- a/scripts/mkdocs-postprocess.js
+++ b/scripts/mkdocs-postprocess.js
@@ -8,7 +8,7 @@ const fs = require('fs-extra');
 
 const destPath_JS = "src/assets/docs/javascripts";
 const destPath_FR_JS = "src/assets/docs/fr/javascripts"; // pour la compilation en local (français)
-const destPath_EN_JS = "src/assets/docs/fr/javascripts"; // pour la compilation en local (anglais)
+const destPath_EN_JS = "src/assets/docs/en/javascripts"; // pour la compilation en local (anglais)
 
 const destPath_CSS = "src/assets/docs/stylesheets";
 const destPath_FR_CSS = "src/assets/docs/fr/stylesheets"; // pour la compilation en local (français)