diff --git a/biscuit/apps/chronos/locale/ar/LC_MESSAGES/django.po b/biscuit/apps/chronos/locale/ar/LC_MESSAGES/django.po
index 8c1ed97b3e31b21bae80a69e8647069d8f975f20..efae3f420eb639e7e3abe41af0e7ddbb3cdb99d7 100644
--- a/biscuit/apps/chronos/locale/ar/LC_MESSAGES/django.po
+++ b/biscuit/apps/chronos/locale/ar/LC_MESSAGES/django.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2019-09-07 23:31+0200\n"
+"POT-Creation-Date: 2019-09-15 14:11+0200\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -35,8 +35,7 @@ msgstr ""
 msgid "Timetables"
 msgstr ""
 
-#: menus.py:12 templates/chronos/tt_week.html:11
-#: templates/chronos/tt_week.html:13
+#: menus.py:12 templates/chronos/tt_week.html:11 views.py:94
 msgid "Timetable"
 msgstr ""
 
@@ -120,11 +119,11 @@ msgstr ""
 msgid "Effective end date of lesson"
 msgstr ""
 
-#: models.py:111
+#: models.py:118
 msgid "Week"
 msgstr ""
 
-#: models.py:128
+#: models.py:135
 msgid "Lessons can only be either substituted or cancelled."
 msgstr ""
 
@@ -145,26 +144,34 @@ msgstr ""
 msgid "Edit substitution"
 msgstr ""
 
-#: templates/chronos/edit_substitution.html:25
+#: templates/chronos/edit_substitution.html:26
 msgid "Save"
 msgstr ""
 
-#: templates/chronos/lessons_day.html:7 templates/chronos/lessons_day.html:9
+#: templates/chronos/lessons_day.html:7 views.py:130
 msgid "Lessons"
 msgstr ""
 
-#: templates/chronos/tt_week.html:35
+#: templates/chronos/tt_week.html:19
 msgid "Select"
 msgstr ""
 
-#: templates/chronos/tt_week.html:46
+#: templates/chronos/tt_week.html:30
 msgid "Times"
 msgstr ""
 
-#: views.py:154
+#: util.py:40
+msgid "Kalenderwoche"
+msgstr ""
+
+#: util.py:40
+msgid "to"
+msgstr ""
+
+#: views.py:164
 msgid "The substitution has been saved."
 msgstr ""
 
-#: views.py:170
+#: views.py:183
 msgid "The substitution has been deleted."
 msgstr ""
diff --git a/biscuit/apps/chronos/locale/de_DE/LC_MESSAGES/django.po b/biscuit/apps/chronos/locale/de_DE/LC_MESSAGES/django.po
index 11ed40e7f025cf0e9cbeb132c9a81da2e30771e4..84dae7d91e08b1bd8a455c28cdc55dc370b1b360 100644
--- a/biscuit/apps/chronos/locale/de_DE/LC_MESSAGES/django.po
+++ b/biscuit/apps/chronos/locale/de_DE/LC_MESSAGES/django.po
@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: \n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2019-09-07 23:31+0200\n"
+"POT-Creation-Date: 2019-09-15 14:11+0200\n"
 "PO-Revision-Date: 2019-09-07 22:04+0000\n"
 "Last-Translator: Tom Teichler <tom.teichler@teckids.org>\n"
 "Language-Team: German <https://translate.edugit.org/projects/biscuit-sis/"
@@ -35,8 +35,7 @@ msgstr "Raum"
 msgid "Timetables"
 msgstr "Stundenpläne"
 
-#: menus.py:12 templates/chronos/tt_week.html:11
-#: templates/chronos/tt_week.html:13
+#: menus.py:12 templates/chronos/tt_week.html:11 views.py:94
 msgid "Timetable"
 msgstr "Stundenplan"
 
@@ -120,13 +119,14 @@ msgstr "Effektives Startdatum des Unterrichts"
 msgid "Effective end date of lesson"
 msgstr "Effektives Enddatum des Unterrichts"
 
-#: models.py:111
+#: models.py:118
 msgid "Week"
 msgstr "Woche"
 
-#: models.py:128
+#: models.py:135
 msgid "Lessons can only be either substituted or cancelled."
-msgstr "Unterrichtsstunden können nur entweder vertreten werden oder ausfallen."
+msgstr ""
+"Unterrichtsstunden können nur entweder vertreten werden oder ausfallen."
 
 #: tables.py:28
 msgid "Groups"
@@ -145,27 +145,35 @@ msgstr "Vertretung"
 msgid "Edit substitution"
 msgstr "Vertretung bearbeiten"
 
-#: templates/chronos/edit_substitution.html:25
+#: templates/chronos/edit_substitution.html:26
 msgid "Save"
 msgstr "Speichern"
 
-#: templates/chronos/lessons_day.html:7 templates/chronos/lessons_day.html:9
+#: templates/chronos/lessons_day.html:7 views.py:130
 msgid "Lessons"
 msgstr "Unterrichtsstunden"
 
-#: templates/chronos/tt_week.html:35
+#: templates/chronos/tt_week.html:19
 msgid "Select"
 msgstr "Auswählen"
 
-#: templates/chronos/tt_week.html:46
+#: templates/chronos/tt_week.html:30
 msgid "Times"
 msgstr "Zeiten"
 
-#: views.py:154
+#: util.py:40
+msgid "Kalenderwoche"
+msgstr ""
+
+#: util.py:40
+msgid "to"
+msgstr ""
+
+#: views.py:164
 msgid "The substitution has been saved."
 msgstr "Die Vertretung wurde gespeichert."
 
-#: views.py:170
+#: views.py:183
 msgid "The substitution has been deleted."
 msgstr "Die Vertretung wurde gelöscht."
 
diff --git a/biscuit/apps/chronos/locale/fr/LC_MESSAGES/django.po b/biscuit/apps/chronos/locale/fr/LC_MESSAGES/django.po
index 30fac8b681e4affc304506fbe95f063e34a50707..b14c086bedd3741b8816cd04d109e2363dd99d71 100644
--- a/biscuit/apps/chronos/locale/fr/LC_MESSAGES/django.po
+++ b/biscuit/apps/chronos/locale/fr/LC_MESSAGES/django.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2019-09-07 23:31+0200\n"
+"POT-Creation-Date: 2019-09-15 14:11+0200\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -34,8 +34,7 @@ msgstr ""
 msgid "Timetables"
 msgstr ""
 
-#: menus.py:12 templates/chronos/tt_week.html:11
-#: templates/chronos/tt_week.html:13
+#: menus.py:12 templates/chronos/tt_week.html:11 views.py:94
 msgid "Timetable"
 msgstr ""
 
@@ -119,11 +118,11 @@ msgstr ""
 msgid "Effective end date of lesson"
 msgstr ""
 
-#: models.py:111
+#: models.py:118
 msgid "Week"
 msgstr ""
 
-#: models.py:128
+#: models.py:135
 msgid "Lessons can only be either substituted or cancelled."
 msgstr ""
 
@@ -144,26 +143,34 @@ msgstr ""
 msgid "Edit substitution"
 msgstr ""
 
-#: templates/chronos/edit_substitution.html:25
+#: templates/chronos/edit_substitution.html:26
 msgid "Save"
 msgstr ""
 
-#: templates/chronos/lessons_day.html:7 templates/chronos/lessons_day.html:9
+#: templates/chronos/lessons_day.html:7 views.py:130
 msgid "Lessons"
 msgstr ""
 
-#: templates/chronos/tt_week.html:35
+#: templates/chronos/tt_week.html:19
 msgid "Select"
 msgstr ""
 
-#: templates/chronos/tt_week.html:46
+#: templates/chronos/tt_week.html:30
 msgid "Times"
 msgstr ""
 
-#: views.py:154
+#: util.py:40
+msgid "Kalenderwoche"
+msgstr ""
+
+#: util.py:40
+msgid "to"
+msgstr ""
+
+#: views.py:164
 msgid "The substitution has been saved."
 msgstr ""
 
-#: views.py:170
+#: views.py:183
 msgid "The substitution has been deleted."
 msgstr ""
diff --git a/biscuit/apps/chronos/locale/nb_NO/LC_MESSAGES/django.po b/biscuit/apps/chronos/locale/nb_NO/LC_MESSAGES/django.po
index aabc3ae72349a556f8ef277b1a64ad9132bfb924..f4f2f09b0e28326b127c90b48bb85411408f0aad 100644
--- a/biscuit/apps/chronos/locale/nb_NO/LC_MESSAGES/django.po
+++ b/biscuit/apps/chronos/locale/nb_NO/LC_MESSAGES/django.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2019-09-07 23:31+0200\n"
+"POT-Creation-Date: 2019-09-15 14:11+0200\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -33,8 +33,7 @@ msgstr ""
 msgid "Timetables"
 msgstr ""
 
-#: menus.py:12 templates/chronos/tt_week.html:11
-#: templates/chronos/tt_week.html:13
+#: menus.py:12 templates/chronos/tt_week.html:11 views.py:94
 msgid "Timetable"
 msgstr ""
 
@@ -118,11 +117,11 @@ msgstr ""
 msgid "Effective end date of lesson"
 msgstr ""
 
-#: models.py:111
+#: models.py:118
 msgid "Week"
 msgstr ""
 
-#: models.py:128
+#: models.py:135
 msgid "Lessons can only be either substituted or cancelled."
 msgstr ""
 
@@ -143,26 +142,34 @@ msgstr ""
 msgid "Edit substitution"
 msgstr ""
 
-#: templates/chronos/edit_substitution.html:25
+#: templates/chronos/edit_substitution.html:26
 msgid "Save"
 msgstr ""
 
-#: templates/chronos/lessons_day.html:7 templates/chronos/lessons_day.html:9
+#: templates/chronos/lessons_day.html:7 views.py:130
 msgid "Lessons"
 msgstr ""
 
-#: templates/chronos/tt_week.html:35
+#: templates/chronos/tt_week.html:19
 msgid "Select"
 msgstr ""
 
-#: templates/chronos/tt_week.html:46
+#: templates/chronos/tt_week.html:30
 msgid "Times"
 msgstr ""
 
-#: views.py:154
+#: util.py:40
+msgid "Kalenderwoche"
+msgstr ""
+
+#: util.py:40
+msgid "to"
+msgstr ""
+
+#: views.py:164
 msgid "The substitution has been saved."
 msgstr ""
 
-#: views.py:170
+#: views.py:183
 msgid "The substitution has been deleted."
 msgstr ""
diff --git a/biscuit/apps/chronos/locale/tr_TR/LC_MESSAGES/django.po b/biscuit/apps/chronos/locale/tr_TR/LC_MESSAGES/django.po
index aabc3ae72349a556f8ef277b1a64ad9132bfb924..f4f2f09b0e28326b127c90b48bb85411408f0aad 100644
--- a/biscuit/apps/chronos/locale/tr_TR/LC_MESSAGES/django.po
+++ b/biscuit/apps/chronos/locale/tr_TR/LC_MESSAGES/django.po
@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2019-09-07 23:31+0200\n"
+"POT-Creation-Date: 2019-09-15 14:11+0200\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -33,8 +33,7 @@ msgstr ""
 msgid "Timetables"
 msgstr ""
 
-#: menus.py:12 templates/chronos/tt_week.html:11
-#: templates/chronos/tt_week.html:13
+#: menus.py:12 templates/chronos/tt_week.html:11 views.py:94
 msgid "Timetable"
 msgstr ""
 
@@ -118,11 +117,11 @@ msgstr ""
 msgid "Effective end date of lesson"
 msgstr ""
 
-#: models.py:111
+#: models.py:118
 msgid "Week"
 msgstr ""
 
-#: models.py:128
+#: models.py:135
 msgid "Lessons can only be either substituted or cancelled."
 msgstr ""
 
@@ -143,26 +142,34 @@ msgstr ""
 msgid "Edit substitution"
 msgstr ""
 
-#: templates/chronos/edit_substitution.html:25
+#: templates/chronos/edit_substitution.html:26
 msgid "Save"
 msgstr ""
 
-#: templates/chronos/lessons_day.html:7 templates/chronos/lessons_day.html:9
+#: templates/chronos/lessons_day.html:7 views.py:130
 msgid "Lessons"
 msgstr ""
 
-#: templates/chronos/tt_week.html:35
+#: templates/chronos/tt_week.html:19
 msgid "Select"
 msgstr ""
 
-#: templates/chronos/tt_week.html:46
+#: templates/chronos/tt_week.html:30
 msgid "Times"
 msgstr ""
 
-#: views.py:154
+#: util.py:40
+msgid "Kalenderwoche"
+msgstr ""
+
+#: util.py:40
+msgid "to"
+msgstr ""
+
+#: views.py:164
 msgid "The substitution has been saved."
 msgstr ""
 
-#: views.py:170
+#: views.py:183
 msgid "The substitution has been deleted."
 msgstr ""