diff --git a/scripts/courses.py b/scripts/courses.py
index 2a63bef..ba68b15 100644
--- a/scripts/courses.py
+++ b/scripts/courses.py
@@ -2,6 +2,7 @@
 import warnings
 
 import yaml
+from typing import List
 
 from config import ROOT, CURRENT_COURSE_ROOT, CURRENT_COURSE_SYMLINK, CURRENT_COURSE_WATCH_FILE, COURSE_IGNORE_FILE, \
     COURSE_INFO_FILE_NAME, FALLBACK_COURSE_INFO_FILE
@@ -31,7 +32,7 @@ class Course:
         self._notes = None
 
     @property
-    def notes(self):
+    def notes(self) -> Notes:
         if not self._notes:
             self._notes = Notes(self)
         return self._notes
@@ -42,7 +43,7 @@ class Course:
         return self.path == other.path
 
 
-def ignored_courses():
+def ignored_courses() -> List[Course]:
     if (ROOT / COURSE_IGNORE_FILE).is_file():
         with open(ROOT / COURSE_IGNORE_FILE) as ignore:
             lines = ignore.readlines()
@@ -53,7 +54,7 @@ def ignored_courses():
     return []
 
 
-def read_files():
+def read_files() -> List[Course]:
     course_directories = [x for x in ROOT.iterdir() if x.is_dir() and x not in ignored_courses()]
     _courses = [Course(path) for path in course_directories]
     return sorted(_courses, key=lambda c: c.name)
@@ -64,7 +65,7 @@ class Courses(list):
         list.__init__(self, read_files())
 
     @property
-    def current(self):
+    def current(self) -> Course:
         return Course(CURRENT_COURSE_ROOT.resolve())
 
     @current.setter
diff --git a/scripts/notes.py b/scripts/notes.py
index b14ccbb..533ae35 100644
--- a/scripts/notes.py
+++ b/scripts/notes.py
@@ -1,6 +1,7 @@
 #!/usr/bin/python3
 import subprocess
 from pathlib import Path
+from typing import Dict
 
 from config import LECTURE_START_MARKER, LECTURE_END_MARKER, DEFAULT_IMPORT_INDENTATION
 from edit import edit
@@ -10,12 +11,12 @@ from parse_counters import parse_counters, dict2setcounters
 
 class Notes:
     def __init__(self, course):
-        self.course = course
-        self.info = course.info['notes']
-        self.root = course.path / self.info['path']
+        self.course = course  # A course
+        self.info: Dict = course.info['notes']
+        self.root: Path = course.path / self.info['path']
         self.root.mkdir(parents=True, exist_ok=True)
-        self.master_file = self.root / self.info['master_file']
-        self.full_file = self.root / self.info['full_file']
+        self.master_file: Path = self.root / self.info['master_file']
+        self.full_file: Path = self.root / self.info['full_file']
         self._lectures = None
 
     @staticmethod
@@ -80,6 +81,20 @@ class Notes:
     def edit_full(self):
         edit(self.full_file)
 
+    def open_master(self):
+        result = subprocess.run(
+            ['zathura', str(self.master_file.with_suffix('.pdf'))],
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL
+        )
+
+    def open_full(self):
+        result = subprocess.run(
+            ['zathura', str(self.full_file.with_suffix('.pdf'))],
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL
+        )
+
     def compile_master(self):
         result = subprocess.run(
             ['latexmk', '-f', '-interaction=nonstopmode', str(self.master_file)],