diff --git a/README.md b/README.md
index 92c2ebf..a260581 100644
--- a/README.md
+++ b/README.md
@@ -16,16 +16,16 @@ that iteratively build on each other.
 ### Data Cleaning
 
 The UDP provided its raw data as a PostgreSQL dump.
-This [notebook](https://nbviewer.jupyter.org/github/webartifex/urban-meal-delivery/blob/develop/research/01_clean_data.ipynb)
+This [notebook](https://nbviewer.jupyter.org/github/webartifex/urban-meal-delivery/blob/main/research/01_clean_data.ipynb)
 cleans the data extensively
-and maps them onto the [ORM models](https://github.com/webartifex/urban-meal-delivery/tree/develop/src/urban_meal_delivery/db)
+and maps them onto the [ORM models](https://github.com/webartifex/urban-meal-delivery/tree/main/src/urban_meal_delivery/db)
 defined in the `urban-meal-delivery` package
-that is developed in the [src/](https://github.com/webartifex/urban-meal-delivery/tree/develop/src) folder
+that is developed in the [src/](https://github.com/webartifex/urban-meal-delivery/tree/main/src) folder
 and contains all source code to drive the analyses.
 
 Due to a non-disclosure agreement with the UDP,
 neither the raw nor the cleaned data are published as of now.
-However, previews of the data can be seen throughout the [research/](https://github.com/webartifex/urban-meal-delivery/tree/develop/research) folder.
+However, previews of the data can be seen throughout the [research/](https://github.com/webartifex/urban-meal-delivery/tree/main/research) folder.
 
 
 ### Tactical Demand Forecasting
@@ -34,9 +34,9 @@ Before any optimizations of the UDP's operations are done,
 a **demand forecasting** system for *tactical* purposes is implemented.
 To achieve that, the cities first undergo a **gridification** step
 where each *pickup* location is assigned into a pixel on a "checker board"-like grid.
-The main part of the source code that implements that is in this [file](https://github.com/webartifex/urban-meal-delivery/blob/develop/src/urban_meal_delivery/db/grids.py#L60).
-Visualizations of the various grids can be found in the [visualizations/](https://github.com/webartifex/urban-meal-delivery/tree/develop/research/visualizations) folder
-and in this [notebook](https://nbviewer.jupyter.org/github/webartifex/urban-meal-delivery/blob/develop/research/03_grid_visualizations.ipynb).
+The main part of the source code that implements that is in this [file](https://github.com/webartifex/urban-meal-delivery/blob/main/src/urban_meal_delivery/db/grids.py#L60).
+Visualizations of the various grids can be found in the [visualizations/](https://github.com/webartifex/urban-meal-delivery/tree/main/research/visualizations) folder
+and in this [notebook](https://nbviewer.jupyter.org/github/webartifex/urban-meal-delivery/blob/main/research/03_grid_visualizations.ipynb).
 
 Then, demand is aggregated on a per-pixel level
 and different kinds of order time series are generated.
@@ -47,7 +47,7 @@ The details of how this works can be found in the first academic paper
 published in the context of this research project
 and titled "*Real-time Demand Forecasting for an Urban Delivery Platform*"
 (cf., the [repository](https://github.com/webartifex/urban-meal-delivery-demand-forecasting) with the LaTeX files).
-All demand forecasting related code is in the [forecasts/](https://github.com/webartifex/urban-meal-delivery/tree/develop/src/urban_meal_delivery/forecasts) sub-package.
+All demand forecasting related code is in the [forecasts/](https://github.com/webartifex/urban-meal-delivery/tree/main/src/urban_meal_delivery/forecasts) sub-package.
 
 
 ### Predictive Routing
@@ -71,11 +71,11 @@ and
 `poetry install --extras research`
 
 The `--extras` option is necessary as the non-develop dependencies
-are structured in the [pyproject.toml](https://github.com/webartifex/urban-meal-delivery/blob/develop/pyproject.toml) file
+are structured in the [pyproject.toml](https://github.com/webartifex/urban-meal-delivery/blob/main/pyproject.toml) file
 into dependencies related to only the `urban-meal-delivery` source code package
 and dependencies used to run the [Jupyter](https://jupyter.org/) environment
 with the analyses.
 
 Contributions are welcome.
 Use the [issues](https://github.com/webartifex/urban-meal-delivery/issues) tab.
-The project is licensed under the [MIT license](https://github.com/webartifex/urban-meal-delivery/blob/develop/LICENSE.txt).
+The project is licensed under the [MIT license](https://github.com/webartifex/urban-meal-delivery/blob/main/LICENSE.txt).
diff --git a/pyproject.toml b/pyproject.toml
index b268891..0e301da 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -9,7 +9,7 @@ target-version = ["py38"]
 
 [tool.poetry]
 name = "urban-meal-delivery"
-version = "0.4.0.dev0"
+version = "0.4.0"
 
 authors = ["Alexander Hess <alexander@webartifex.biz>"]
 description = "Optimizing an urban meal delivery platform"
diff --git a/research/01_clean_data.ipynb b/research/01_clean_data.ipynb
index 1d9f6fb..c3de005 100644
--- a/research/01_clean_data.ipynb
+++ b/research/01_clean_data.ipynb
@@ -19,7 +19,7 @@
     "- numeric columns are checked for plausibility\n",
     "- foreign key relationships are strictly enforced\n",
     "\n",
-    "The structure of the data can be viewed at the [ORM layer](https://github.com/webartifex/urban-meal-delivery/tree/develop/src/urban_meal_delivery/db) in the package."
+    "The structure of the data can be viewed at the [ORM layer](https://github.com/webartifex/urban-meal-delivery/tree/main/src/urban_meal_delivery/db) in the package."
    ]
   },
   {