diff --git a/pyssp/system.py b/pyssp/system.py
index 9ac5af1..5fdb7f9 100644
--- a/pyssp/system.py
+++ b/pyssp/system.py
@@ -32,6 +32,7 @@ def harmonic(A: int, process: None | Generator = None) -> NoReturn:
 
 def white_noise(variance: float) -> NoReturn:
     """The harmonic random process.
+
     Page 93.
 
     """