diff --git a/ppocr/modeling/backbones/rec_resnet_aster.py b/ppocr/modeling/backbones/rec_resnet_aster.py
index bdecaf46af98f9b967d9a339f82d4e938abdc6d9..6a2710dfa079b4d910146c10ca2cff31321b2513 100644
--- a/ppocr/modeling/backbones/rec_resnet_aster.py
+++ b/ppocr/modeling/backbones/rec_resnet_aster.py
@@ -11,7 +11,10 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
+"""
+This code is refer from:
+https://github.com/ayumiymk/aster.pytorch/blob/master/lib/models/resnet_aster.py
+"""
 import paddle
 import paddle.nn as nn
 
diff --git a/ppocr/modeling/heads/rec_aster_head.py b/ppocr/modeling/heads/rec_aster_head.py
index 4961897b409020fe6cff72eb96f3257156fa33ac..9240f002d3a8bcbde517142be6b45559430de610 100644
--- a/ppocr/modeling/heads/rec_aster_head.py
+++ b/ppocr/modeling/heads/rec_aster_head.py
@@ -11,6 +11,10 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""
+This code is refer from:
+https://github.com/ayumiymk/aster.pytorch/blob/master/lib/models/attention_recognition_head.py
+"""
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
diff --git a/ppocr/modeling/transforms/stn.py b/ppocr/modeling/transforms/stn.py
index 215895f4c4c719f407f4998f7429d965e0529ddc..6f2bdda050f217d8253740001901fbff4065782a 100644
--- a/ppocr/modeling/transforms/stn.py
+++ b/ppocr/modeling/transforms/stn.py
@@ -11,7 +11,10 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
+"""
+This code is refer from:
+https://github.com/ayumiymk/aster.pytorch/blob/master/lib/models/stn_head.py
+"""
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
diff --git a/ppocr/modeling/transforms/tps_spatial_transformer.py b/ppocr/modeling/transforms/tps_spatial_transformer.py
index b510acb0d4012c9a4d90c7ca07cac895f0bf242e..4db34f7b4833c1c9b2901c68899bfb294b5843c4 100644
--- a/ppocr/modeling/transforms/tps_spatial_transformer.py
+++ b/ppocr/modeling/transforms/tps_spatial_transformer.py
@@ -11,6 +11,10 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+"""
+This code is refer from:
+https://github.com/ayumiymk/aster.pytorch/blob/master/lib/models/tps_spatial_transformer.py
+"""
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function