diff --git a/audio/paddleaudio/features/core.py b/audio/paddleaudio/features/core.py
index f53f60f31f59849a253c27a1bc7141e7f5ae05a0..dd25724ff22254ced39e4387e24ccdc411148b12 100644
--- a/audio/paddleaudio/features/core.py
+++ b/audio/paddleaudio/features/core.py
@@ -11,6 +11,7 @@
 # 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.
+# Modified from librosa(https://github.com/librosa/librosa)
 import warnings
 from typing import List
 from typing import Optional
diff --git a/docs/source/reference.md b/docs/source/reference.md
index ac704cb08cb298f3ed50ccc7fcb3540825680b12..39c7afe5a2029f060d98c867ca40ded436bc83d9 100644
--- a/docs/source/reference.md
+++ b/docs/source/reference.md
@@ -31,3 +31,7 @@ We borrowed a lot of code from these repos to build `model` and `engine`, thank
 * [chainer](https://github.com/chainer/chainer/blob/master/LICENSE)
 - MIT License
 - Updater, Trainer and more utils.
+
+* [librosa](https://github.com/librosa/librosa/blob/main/LICENSE.md)
+- ISC License
+- Audio feature