diff --git a/ppocr/losses/det_basic_loss.py b/ppocr/losses/det_basic_loss.py
index 7017236c284e55710f242275a413d56d32158d34..61ea579b41d3cdf7831c168f563a1e3cd72463a0 100644
--- a/ppocr/losses/det_basic_loss.py
+++ b/ppocr/losses/det_basic_loss.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/WenmuZhou/DBNet.pytorch/blob/master/models/losses/basic_loss.py
+"""
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
@@ -147,4 +150,4 @@ class BCELoss(nn.Layer):
 
     def forward(self, input, label, mask=None, weight=None, name=None):
         loss = F.binary_cross_entropy(input, label, reduction=self.reduction)
-        return loss
\ No newline at end of file
+        return loss
diff --git a/ppocr/losses/det_db_loss.py b/ppocr/losses/det_db_loss.py
index b079aabff7c7deccc7e365b91c9407f7e894bcb9..708ffbdb47f349304e2bfd781a836e79348475f4 100755
--- a/ppocr/losses/det_db_loss.py
+++ b/ppocr/losses/det_db_loss.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/WenmuZhou/DBNet.pytorch/blob/master/models/losses/DB_loss.py
+"""
 
 from __future__ import absolute_import
 from __future__ import division
diff --git a/ppocr/modeling/transforms/tps.py b/ppocr/modeling/transforms/tps.py
index 6cd68555369dd1ddbd6ccf5236688a4b957b8525..9bdab0f85112b90d8da959dce4e258188a812052 100644
--- a/ppocr/modeling/transforms/tps.py
+++ b/ppocr/modeling/transforms/tps.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/clovaai/deep-text-recognition-benchmark/blob/master/modules/transformation.py
+"""
 
 from __future__ import absolute_import
 from __future__ import division