diff --git a/Programming/anaconda/2019.07/conda-env-defs/datascience_py36/datascience_36.yml b/Programming/anaconda/2019.07/conda-env-defs/datascience_py36/datascience_36.yml
index 8f9f851..74bf6e4 100644
--- a/Programming/anaconda/2019.07/conda-env-defs/datascience_py36/datascience_36.yml
+++ b/Programming/anaconda/2019.07/conda-env-defs/datascience_py36/datascience_36.yml
@@ -17,6 +17,8 @@ dependencies:
   - deap
   - nb_conda_kernels
   - ipywidgets
+  - plotly
+  - python-graphviz
 # Note that the dask 2.1.0 with python 3.6 led to a non-functioning configuration
 # (serialization errors in dask). Therefore we exclude it here.
 #  - dask
diff --git a/Programming/anaconda/2019.07/conda-env-defs/datascience_py37/datascience_py37.yml b/Programming/anaconda/2019.07/conda-env-defs/datascience_py37/datascience_py37.yml
index 7eeab07..324ef2b 100644
--- a/Programming/anaconda/2019.07/conda-env-defs/datascience_py37/datascience_py37.yml
+++ b/Programming/anaconda/2019.07/conda-env-defs/datascience_py37/datascience_py37.yml
@@ -18,5 +18,7 @@ dependencies:
   - deap
   - nb_conda_kernels
   - ipywidgets
+  - plotly
   - dask
   - dask-jobqueue
+  - python-graphviz