diff --git a/pm4py/algo/filtering/pandas/prefixes/__init__.py b/pm4py/algo/filtering/pandas/prefixes/__init__.py
index ff7a77c0f..bfe1e96ba 100644
--- a/pm4py/algo/filtering/pandas/prefixes/__init__.py
+++ b/pm4py/algo/filtering/pandas/prefixes/__init__.py
@@ -1 +1,18 @@
+'''
+    This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
+
+    PM4Py is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    PM4Py is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PM4Py.  If not, see <https://www.gnu.org/licenses/>.
+'''
+
 from pm4py.algo.filtering.pandas.prefixes import prefix_filter
diff --git a/pm4py/algo/filtering/pandas/prefixes/prefix_filter.py b/pm4py/algo/filtering/pandas/prefixes/prefix_filter.py
index 36a1186a5..4a64bb258 100644
--- a/pm4py/algo/filtering/pandas/prefixes/prefix_filter.py
+++ b/pm4py/algo/filtering/pandas/prefixes/prefix_filter.py
@@ -1,3 +1,20 @@
+'''
+    This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
+
+    PM4Py is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    PM4Py is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PM4Py.  If not, see <https://www.gnu.org/licenses/>.
+'''
+
 import pandas as pd
 
 from enum import Enum
diff --git a/pm4py/algo/filtering/pandas/suffixes/__init__.py b/pm4py/algo/filtering/pandas/suffixes/__init__.py
index e69de29bb..be585a556 100644
--- a/pm4py/algo/filtering/pandas/suffixes/__init__.py
+++ b/pm4py/algo/filtering/pandas/suffixes/__init__.py
@@ -0,0 +1,17 @@
+'''
+    This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
+
+    PM4Py is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    PM4Py is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PM4Py.  If not, see <https://www.gnu.org/licenses/>.
+'''
+
diff --git a/pm4py/algo/filtering/pandas/suffixes/suffix_filter.py b/pm4py/algo/filtering/pandas/suffixes/suffix_filter.py
index d4e2b8bbf..8f2c931cb 100644
--- a/pm4py/algo/filtering/pandas/suffixes/suffix_filter.py
+++ b/pm4py/algo/filtering/pandas/suffixes/suffix_filter.py
@@ -1,3 +1,20 @@
+'''
+    This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
+
+    PM4Py is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    PM4Py is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PM4Py.  If not, see <https://www.gnu.org/licenses/>.
+'''
+
 import pandas as pd
 
 from enum import Enum
diff --git a/pm4py/algo/transformation/ocel/features/events/related_objects_features.py b/pm4py/algo/transformation/ocel/features/events/related_objects_features.py
index 61d3d6d64..52f95f9f2 100644
--- a/pm4py/algo/transformation/ocel/features/events/related_objects_features.py
+++ b/pm4py/algo/transformation/ocel/features/events/related_objects_features.py
@@ -1,3 +1,20 @@
+'''
+    This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
+
+    PM4Py is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    PM4Py is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PM4Py.  If not, see <https://www.gnu.org/licenses/>.
+'''
+
 from pm4py.objects.ocel.obj import OCEL
 from typing import Optional, Dict, Any
 
diff --git a/pm4py/algo/transformation/ocel/features/objects/obj_con_in_graph_features.py b/pm4py/algo/transformation/ocel/features/objects/obj_con_in_graph_features.py
index 1dfa7af7e..8d75f4730 100644
--- a/pm4py/algo/transformation/ocel/features/objects/obj_con_in_graph_features.py
+++ b/pm4py/algo/transformation/ocel/features/objects/obj_con_in_graph_features.py
@@ -1,3 +1,20 @@
+'''
+    This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
+
+    PM4Py is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    PM4Py is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PM4Py.  If not, see <https://www.gnu.org/licenses/>.
+'''
+
 from pm4py.objects.ocel.obj import OCEL
 from typing import Optional, Dict, Any
 from enum import Enum
diff --git a/pm4py/algo/transformation/ocel/features/objects/related_activities_features.py b/pm4py/algo/transformation/ocel/features/objects/related_activities_features.py
index f16b9b2da..ca3b8bc7d 100644
--- a/pm4py/algo/transformation/ocel/features/objects/related_activities_features.py
+++ b/pm4py/algo/transformation/ocel/features/objects/related_activities_features.py
@@ -1,3 +1,20 @@
+'''
+    This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
+
+    PM4Py is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    PM4Py is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PM4Py.  If not, see <https://www.gnu.org/licenses/>.
+'''
+
 from pm4py.objects.ocel.obj import OCEL
 from typing import Optional, Dict, Any
 
diff --git a/pm4py/algo/transformation/ocel/features/objects/related_events_features.py b/pm4py/algo/transformation/ocel/features/objects/related_events_features.py
index 34f25aa22..e2cfeac96 100644
--- a/pm4py/algo/transformation/ocel/features/objects/related_events_features.py
+++ b/pm4py/algo/transformation/ocel/features/objects/related_events_features.py
@@ -1,3 +1,20 @@
+'''
+    This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
+
+    PM4Py is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    PM4Py is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PM4Py.  If not, see <https://www.gnu.org/licenses/>.
+'''
+
 from pm4py.objects.ocel.obj import OCEL
 from typing import Optional, Dict, Any
 
diff --git a/pm4py/objects/ocel/util/ev_att_to_obj_type.py b/pm4py/objects/ocel/util/ev_att_to_obj_type.py
index 659d4f0b3..45d192975 100644
--- a/pm4py/objects/ocel/util/ev_att_to_obj_type.py
+++ b/pm4py/objects/ocel/util/ev_att_to_obj_type.py
@@ -1,3 +1,20 @@
+'''
+    This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
+
+    PM4Py is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    PM4Py is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PM4Py.  If not, see <https://www.gnu.org/licenses/>.
+'''
+
 from pm4py.objects.ocel.obj import OCEL
 from typing import Optional, Dict, Any
 from enum import Enum
diff --git a/pm4py/visualization/heuristics_net/variants/pydotplus_vis.py b/pm4py/visualization/heuristics_net/variants/pydotplus_vis.py
index 6d9198c64..102a7a5ad 100644
--- a/pm4py/visualization/heuristics_net/variants/pydotplus_vis.py
+++ b/pm4py/visualization/heuristics_net/variants/pydotplus_vis.py
@@ -1,3 +1,20 @@
+'''
+    This file is part of PM4Py (More Info: https://pm4py.fit.fraunhofer.de).
+
+    PM4Py is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    PM4Py is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with PM4Py.  If not, see <https://www.gnu.org/licenses/>.
+'''
+
 import math
 import tempfile