diff --git a/csst_common/data_manager.py b/csst_common/data_manager.py
index cabe7337c1451a461cd38a5306ea6449f57b92c8..51847914479cfe52c0e4b83e0a5a55e4c8d4a57b 100644
--- a/csst_common/data_manager.py
+++ b/csst_common/data_manager.py
@@ -545,6 +545,20 @@ class CsstMsDataManager:
         return os.path.join(self.dir_l1, fn)
 
     def get_refs(self, detector=6):
+        """
+        Parameters
+        ----------
+        detector: int
+            Detector number.
+
+        Returns
+        -------
+        dict
+            {'bias': '/crdsroot/references/msc/csst_msc_ms_bias_11_000001.fits',
+             'dark': '/crdsroot/references/msc/csst_msc_ms_dark_11_000001.fits',
+             'ledflat': '/crdsroot/references/msc/csst_msc_ms_ledflat_11_000001.fits',
+             'shutter': '/crdsroot/references/msc/csst_msc_ms_shutter_11_000001.fits'}
+        """
         if self.crds.is_available:
             return self.crds.retry(
                 self.crds.get_refs, 3,