Fix typos
diff --git a/Doc/library/calendar.rst b/Doc/library/calendar.rst
index d650ff4..2f11aad 100644
--- a/Doc/library/calendar.rst
+++ b/Doc/library/calendar.rst
@@ -16,7 +16,7 @@
are given as integers. For related
functionality, see also the :mod:`datetime` and :mod:`time` modules.
-Most of these functions and classses rely on the :mod:`datetime` module which
+Most of these functions and classes rely on the :mod:`datetime` module which
uses an idealized calendar, the current Gregorian calendar indefinitely extended
in both directions. This matches the definition of the "proleptic Gregorian"
calendar in Dershowitz and Reingold's book "Calendrical Calculations", where