diff --git a/docs/08_open_source_teaching_notes.md b/docs/08_open_source_teaching_notes.md
index d15aaf2..ef8663d 100755
--- a/docs/08_open_source_teaching_notes.md
+++ b/docs/08_open_source_teaching_notes.md
@@ -8,7 +8,7 @@ search_exclude: true
 
 TBD: Summaries for part 2: Digital work in teams
 
-TODO: print playbooks for maintainers ([M1-M3](https://github.com/digital-work-lab/open-source-collaboration-game/blob/main/readme.md))
+TODO: print playbooks for maintainers ([M1-M3](https://github.com/digital-work-lab/open-source-collaboration-game/blob/main/readme.md){: target="_blank"})
 
 # Teaching notes: Open-Source
 
diff --git a/exercises/git_branch/branching_exercise_notebook.md b/exercises/git_branch/branching_exercise_notebook.md
index a844b27..f981ef9 100644
--- a/exercises/git_branch/branching_exercise_notebook.md
+++ b/exercises/git_branch/branching_exercise_notebook.md
@@ -37,7 +37,7 @@ With this notebook, you can practice branching in Git.
 
 We have covered `git commit`, as well as `git branch`, `git switch`, and `git merge` operations in the lecture.
 
-**Task**: To practice branching and manipulating the Git graph, complete level 1 (introduction) of the [learngitbranching](https://learngitbranching.js.org/?locale=en_EN) tutorial.
+**Task**: To practice branching and manipulating the Git graph, complete level 1 (introduction) of the [learngitbranching](https://learngitbranching.js.org/?locale=en_EN){: target="_blank"} tutorial.
 
 Hints:
 
@@ -55,7 +55,7 @@ IFrame('https://learngitbranching.js.org/', width=1400, height=800)
 
 If you have completed Part 1 quickly, you may continue practicing with the following challenge.
 
-**Task**: To continue practicing, create the following tree, which resembles a typical setup of Git branches. To do this, you can open [learngitbranching](https://learngitbranching.js.org/?locale=en_EN) in a separate window.
+**Task**: To continue practicing, create the following tree, which resembles a typical setup of Git branches. To do this, you can open [learngitbranching](https://learngitbranching.js.org/?locale=en_EN){: target="_blank"} in a separate window.
 
 <img src="../../material/git-branches.png" style="width: 600px;" alt="Git branches"/>
 
@@ -152,7 +152,7 @@ There is another option: to **squash** changes from another branch. This effecti
 We will now practice the different methods in a real Git repository.
 
 
-**Task**: Start GitHub Codespaces from the [CoLRev repository](https://github.com/CoLRev-Environment/colrev) and set up the `quality_model_docs` branch, using the following commands.
+**Task**: Start GitHub Codespaces from the [CoLRev repository](https://github.com/CoLRev-Environment/colrev){: target="_blank"} and set up the `quality_model_docs` branch, using the following commands.
 
 ```python
 cd /workspaces/colrev
diff --git a/exercises/git_commit/commit_exercise_notebook.md b/exercises/git_commit/commit_exercise_notebook.md
index 820e605..3804ccd 100644
--- a/exercises/git_commit/commit_exercise_notebook.md
+++ b/exercises/git_commit/commit_exercise_notebook.md
@@ -43,7 +43,7 @@ With this notebook, you can practice committing changes in Git.
 
 ## Part 1: Set up <a id="clone"></a>
 
-**Task**: Start GitHub Codespaces from the [CoLRev repository](https://github.com/CoLRev-Environment/colrev).
+**Task**: Start GitHub Codespaces from the [CoLRev repository](https://github.com/CoLRev-Environment/colrev){: target="_blank"}.
 
 
 **Note**: When starting the Codespace, the repository is **cloned** on a virtual machine (`git clone URL`). To create an empty git project, you would run `git init`.
@@ -238,7 +238,7 @@ It is ok to combine functionality, tests, and docs that belong together in one c
 
 </details>
 
-**Optional**: If you have the time, you may check the [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/) specification.
+**Optional**: If you have the time, you may check the [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/){: target="_blank"} specification.
 
 To create atomic commits, you may need to **add specific lines of code that should go into a commit**, leaving other changes in the working directory.
 
@@ -295,4 +295,4 @@ In this notebook, we have learned to
 - Undo changes
 - Navigate VisualStudio Code on GitHub Codespaces
 
-Remember to delete your codespace [here](https://github.com/codespaces).
+Remember to delete your codespace [here](https://github.com/codespaces){: target="_blank"}.