Add various missing references.
@@ -5154,6 +5154,10 @@ LIGHT_SOURCE_SDS = CaseInsensitiveMapping(LIGHT_SOURCE_RIT_SDS)
LIGHT_SOURCE_SDS.__doc__ = """
Aggregated light sources spectral distributions.
+References
+----------
+:cite:`Houston2015a`, :cite:`Ohno2008a`, :cite:`Pointer1980a`
+
LIGHT_SOURCE_SDS : CaseInsensitiveMapping
"""
