diff --git a/ppcls/utils/ema.py b/ppcls/utils/ema.py
index e41f472d6a1e448e76b922a718befbaa23d6ab51..b54cdb1b2030dc0a70394816a433e7e715e12996 100644
--- a/ppcls/utils/ema.py
+++ b/ppcls/utils/ema.py
@@ -17,6 +17,11 @@ import numpy as np
 
 
 class ExponentialMovingAverage():
+    """
+    Exponential Moving Average
+    Code was heavily based on https://github.com/Wanger-SJTU/SegToolbox.Pytorch/blob/master/lib/utils/ema.py
+    """
+
     def __init__(self, model, decay, thres_steps=True):
         self._model = model
         self._decay = decay
diff --git a/ppcls/utils/misc.py b/ppcls/utils/misc.py
index 90dc47e9bb7e6162ad921a14d24bc5467a415b62..08ab7b6f77cb85b0a822713ee7d573d561762d14 100644
--- a/ppcls/utils/misc.py
+++ b/ppcls/utils/misc.py
@@ -18,6 +18,7 @@ __all__ = ['AverageMeter']
 class AverageMeter(object):
     """
     Computes and stores the average and current value
+    Code was based on https://github.com/pytorch/examples/blob/master/imagenet/main.py
     """
 
     def __init__(self, name='', fmt='f', postfix="", need_avg=True):