diff --git a/.github/workflows/basic-tests.yml b/.github/workflows/basic-tests-linux.yml
similarity index 84%
rename from .github/workflows/basic-tests.yml
rename to .github/workflows/basic-tests-linux.yml
index 2da136d..5a17259 100644
--- a/.github/workflows/basic-tests.yml
+++ b/.github/workflows/basic-tests-linux.yml
@@ -1,16 +1,20 @@
-name: Code tests
+name: Code tests on Linux
 
 on:
   push:
     branches: [ main ]
     paths:
-      - '**/*.py'   # Run workflow for changes in Python files
-      - '**/*.ipynb' # Run workflow for changes in Jupyter notebooks
+      - '**/*.py'    # Run workflow for changes in Python files
+      - '**/*.ipynb'
+      - '**/*.yaml'
+      - '**/*.sh'
   pull_request:
     branches: [ main ]
     paths:
       - '**/*.py'
       - '**/*.ipynb'
+      - '**/*.yaml'
+      - '**/*.sh'
 
 jobs:
   test:
diff --git a/.github/workflows/basic-tests-macos.yml b/.github/workflows/basic-tests-macos.yml
new file mode 100644
index 0000000..23e695e
--- /dev/null
+++ b/.github/workflows/basic-tests-macos.yml
@@ -0,0 +1,47 @@
+name: Code tests on macOS
+
+on:
+  push:
+    branches: [ main ]
+    paths:
+      - '**/*.py'    # Run workflow for changes in Python files
+      - '**/*.ipynb'
+      - '**/*.yaml'
+      - '**/*.sh'
+  pull_request:
+    branches: [ main ]
+    paths:
+      - '**/*.py'
+      - '**/*.ipynb'
+      - '**/*.yaml'
+      - '**/*.sh'
+
+jobs:
+  test:
+    runs-on: macos-latest
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Set up Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: "3.10"
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install pytest nbval
+        if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+
+    - name: Test Selected Python Scripts
+      run: |
+        pytest ch04/01_main-chapter-code/tests.py
+        pytest ch05/01_main-chapter-code/tests.py
+        pytest setup/02_installing-python-libraries/tests.py
+
+    - name: Validate Selected Jupyter Notebooks
+      run: |
+        pytest --nbval ch02/01_main-chapter-code/dataloader.ipynb
+        pytest --nbval ch03/01_main-chapter-code/multihead-attention.ipynb
+        pytest --nbval ch02/04_bonus_dataloader-intuition/dataloader-intuition.ipynb
diff --git a/.github/workflows/basic-tests-windows.yml b/.github/workflows/basic-tests-windows.yml
new file mode 100644
index 0000000..eeb9d79
--- /dev/null
+++ b/.github/workflows/basic-tests-windows.yml
@@ -0,0 +1,51 @@
+name: Code tests on Windows
+
+on:
+  push:
+    branches: [ main ]
+    paths:
+      - '**/*.py'    # Run workflow for changes in Python files
+      - '**/*.ipynb'
+      - '**/*.yaml'
+      - '**/*.sh'
+  pull_request:
+    branches: [ main ]
+    paths:
+      - '**/*.py'
+      - '**/*.ipynb'
+      - '**/*.yaml'
+      - '**/*.sh'
+
+jobs:
+  test:
+    runs-on: windows-latest
+
+    steps:
+      - name: Checkout Code
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.10'
+
+      - name: Install dependencies
+        shell: bash
+        run: |
+          python -m pip install --upgrade pip
+          pip install pytest nbval
+          if [ -f requirements.txt ]; then pip install -r requirements.txt; fi
+
+      - name: Test Selected Python Scripts
+        shell: bash
+        run: |
+          pytest ch04/01_main-chapter-code/tests.py
+          pytest ch05/01_main-chapter-code/tests.py
+          pytest setup/02_installing-python-libraries/tests.py
+
+      - name: Validate Selected Jupyter Notebooks
+        shell: bash
+        run: |
+          pytest --nbval ch02/01_main-chapter-code/dataloader.ipynb
+          pytest --nbval ch03/01_main-chapter-code/multihead-attention.ipynb
+          pytest --nbval ch02/04_bonus_dataloader-intuition/dataloader-intuition.ipynb
diff --git a/README.md b/README.md
index bfeec20..de78e26 100644
--- a/README.md
+++ b/README.md
@@ -37,8 +37,10 @@ Alternatively, you can view this and other files on GitHub at [https://github.co
 
 <br>
 
+[![Code tests on Linux](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/basic-tests-linux.yml/badge.svg)](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/basic-tests-linux.yml)
+[![Code tests on Windows](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/basic-tests-windows.yml/badge.svg?123)](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/basic-tests-windows.yml)
+[![Code tests on macOS](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/basic-tests-macos.yml/badge.svg)](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/basic-tests-macos.yml)
 [![Python PEP8 linting](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/pep8-linter.yml/badge.svg)](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/pep8-linter.yml)
-[![Python tests](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/basic-tests.yml/badge.svg)](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/basic-tests.yml)
 [![Check hyperlinks](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/check-links.yml/badge.svg)](https://github.com/rasbt/LLMs-from-scratch/actions/workflows/check-links.yml)
 
 <br>
diff --git a/ch03/02_bonus_efficient-multihead-attention/ch03.py b/ch03/02_bonus_efficient-multihead-attention/ch03.py
index 0ee3ca9..b6cb9ec 100644
--- a/ch03/02_bonus_efficient-multihead-attention/ch03.py
+++ b/ch03/02_bonus_efficient-multihead-attention/ch03.py
@@ -1,3 +1,11 @@
+# Copyright (c) Sebastian Raschka under Apache License 2.0 (see LICENSE.txt).
+# Source for "Build a Large Language Model From Scratch"
+#   - https://www.manning.com/books/build-a-large-language-model-from-scratch
+# Code: https://github.com/rasbt/LLMs-from-scratch
+#
+# This file contains the relevant code from chapter 3 that is going to be used
+# in forthcoming chapters.
+
 import torch
 import torch.nn as nn