diff --git a/aleksis/apps/chronos/apps.py b/aleksis/apps/chronos/apps.py
index 20005412be9701f19f7ba5ff13b79e4c5baf5f09..66d0b0e7ac22805fe0e06ec444890656676f3200 100644
--- a/aleksis/apps/chronos/apps.py
+++ b/aleksis/apps/chronos/apps.py
@@ -13,6 +13,7 @@ class ChronosConfig(AppConfig):
         ([2018, 2019, 2020], "Jonathan Weth", "wethjo@katharineum.de"),
         ([2018, 2019], "Frank Poetzsch-Heffter", "p-h@katharineum.de"),
         ([2019, 2020], "Dominik George", "dominik.george@teckids.org"),
+        ([2019], "Julian Leucker", "leuckeju@katharineum.de"),
         ([2019], "Tom Teichler", "tom.teichler@teckids.org"),
         ([2019], "Hangzhi Yu", "yuha@katharineum.de"),
     )
diff --git a/aleksis/apps/chronos/util/date.py b/aleksis/apps/chronos/util/date.py
index f17aa0ba8354b9dce1ed9db5ee158954afc71ea0..feb63bc8de2f7e3c9ea0dc68a6d4b187b5c80d0b 100644
--- a/aleksis/apps/chronos/util/date.py
+++ b/aleksis/apps/chronos/util/date.py
@@ -8,19 +8,22 @@ from django.utils.translation import gettext_lazy as _
 
 
 def week_weekday_from_date(when: date) -> Tuple[CalendarWeek, int]:
+    """Return a tuple of week and weekday from a given date."""
     return (CalendarWeek.from_date(when), when.weekday())
 
 
 def week_weekday_to_date(week: CalendarWeek, weekday: int) -> date:
+    """Return a date object for one day in a calendar week."""
     return week[weekday - 1]
 
 
 def week_period_to_date(week: Union[CalendarWeek, int], period) -> date:
+    """Return the date of a lesson period in a given week."""
     return period.get_date(week)
 
 
 def get_weeks_for_year(year: int) -> List[CalendarWeek]:
-    """ Generates all weeks for one year """
+    """Generate all weeks for one year."""
     weeks = []
 
     # Go for all weeks in year and create week list
diff --git a/aleksis/apps/chronos/views.py b/aleksis/apps/chronos/views.py
index 3ddecc1526e257ed0e1196d0cef56e1b78790b71..72821e75ad47d8f112cb507a7f3f7c0d43a66959 100644
--- a/aleksis/apps/chronos/views.py
+++ b/aleksis/apps/chronos/views.py
@@ -26,6 +26,7 @@ from aleksis.core.util.core_helpers import has_person, get_site_preferences
 
 @permission_required("chronos.view_timetable_overview")
 def all_timetables(request: HttpRequest) -> HttpResponse:
+    """View all timetables for persons, groups and rooms."""
     context = {}
 
     teachers = Person.objects.annotate(
@@ -56,6 +57,7 @@ def my_timetable(
     month: Optional[int] = None,
     day: Optional[int] = None,
 ) -> HttpResponse:
+    """View personal timetable on a specified date."""
     context = {}
 
     if day:
@@ -122,6 +124,7 @@ def timetable(
     week: Optional[int] = None,
     regular: Optional[str] = None,
 ) -> HttpResponse:
+    """View a selected timetable for a person, group or room."""
     context = {}
 
     is_smart = regular != "regular"
@@ -183,6 +186,7 @@ def lessons_day(
     month: Optional[int] = None,
     day: Optional[int] = None,
 ) -> HttpResponse:
+    """View all lessons taking place on a specified day."""
     context = {}
 
     if day:
@@ -225,6 +229,7 @@ def get_substitution_by_id(request: HttpRequest, id_: int, week: int):
 
 @permission_required("chronos.edit_substitution", fn=get_substitution_by_id)
 def edit_substitution(request: HttpRequest, id_: int, week: int) -> HttpResponse:
+    """View a form to edit a substitution lessen."""
     context = {}
 
     lesson_period = get_object_or_404(LessonPeriod, pk=id_)
@@ -263,6 +268,10 @@ def edit_substitution(request: HttpRequest, id_: int, week: int) -> HttpResponse
 
 @permission_required("chronos.delete_substitution", fn=get_substitution_by_id)
 def delete_substitution(request: HttpRequest, id_: int, week: int) -> HttpResponse:
+    """Delete a substitution lesson.
+
+    Redirects back to substition list on success.
+    """
     lesson_period = get_object_or_404(LessonPeriod, pk=id_)
     wanted_week = lesson_period.lesson.get_calendar_week(week)
 
@@ -285,6 +294,7 @@ def substitutions(
     day: Optional[int] = None,
     is_print: bool = False,
 ) -> HttpResponse:
+    """View all substitutions on a spcified day."""
     context = {}
 
     if day: