diff --git a/README.md b/README.md
index 9acae29..a1b7227 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,8 @@ meson test -C _build --print-errorlogs
 
 ## License
 
+### DFT-D4 Code
+
 DFT-D4 is free software: you can redistribute it and/or modify it under
 the terms of the GNU Lesser General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
@@ -38,3 +40,21 @@ DFT-D4 is distributed in the hope that it will be useful,
 but without any warranty; without even the implied warranty of
 merchantability or fitness for a particular purpose. See the
 GNU Lesser General Public License for more details.
+
+### ORCA-derived Code in `dftd_cblas.h` and `dftd_matrix.h`
+
+The files [`include/dftd_cblas.h`](https://github.com/dftd4/cpp-d4/blob/main/include/dftd_cblas.h) and
+[`include/dftd_matrix.h`](https://github.com/dftd4/cpp-d4/blob/main/include/dftd_matrix.h)
+contain code adapted from the ORCA quantum chemistry program,
+which is developed by the group of Prof. Frank Neese at the Max-Planck-Institut für Kohlenforschung,
+Mülheim an der Ruhr and FAccTs GmbH. ORCA is licensed by the
+Max-Planck-Institut für Kohlenforschung and FAccTs GmbH.
+
+The inclusion of ORCA code in these files is done with the explicit permission
+of the ORCA developers. This code remains subject to the licensing terms
+of ORCA, which allow free academic use but require a separate license for
+industrial or commercial use.
+
+For reuse or licensing of the code in `dftd_cblas.h` and `dftd_matrix.h`, please contact
+the ORCA team at the Max-Planck-Institut für Kohlenforschung (https://orcaforum.kofo.mpg.de/)
+or FAccTs GmbH. (https://www.faccts.de/).
diff --git a/include/dftd_cblas.h b/include/dftd_cblas.h
index a9ed3a3..1513de8 100644
--- a/include/dftd_cblas.h
+++ b/include/dftd_cblas.h
@@ -1,19 +1,13 @@
-/* This file is part of cpp-d4.
+/*
+ * This file contains code adapted from the ORCA quantum chemistry program.
+ * ORCA is developed by the group of Prof. Frank Neese at the Max-Planck-Institut für Kohlenforschung,
+ * Mülheim an der Ruhr and FAccTs GmbH. ORCA is licensed by the Max-Planck-Institut für Kohlenforschung and FAccTs GmbH.
  *
- * Copyright (C) 2019 Sebastian Ehlert, Marvin Friede
+ * The inclusion of ORCA code in this file has been done with the explicit permission
+ * of the ORCA developers.
  *
- * cpp-d4 is free software: you can redistribute it and/or modify it under
- * the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * cpp-d4 is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with cpp-d4.  If not, see <https://www.gnu.org/licenses/>.
+ * For reuse or licensing of this code, please contact the ORCA team at the Max-Planck-Institut
+ * für Kohlenforschung (https://orcaforum.kofo.mpg.de/) or FAccTs GmbH (https://www.faccts.de/).
  */
 #pragma once
 
diff --git a/include/dftd_matrix.h b/include/dftd_matrix.h
index 401a6e5..79b0e37 100644
--- a/include/dftd_matrix.h
+++ b/include/dftd_matrix.h
@@ -1,19 +1,13 @@
-/* This file is part of cpp-d4.
+/*
+ * This file contains code adapted from the ORCA quantum chemistry program.
+ * ORCA is developed by the group of Prof. Frank Neese at the Max-Planck-Institut für Kohlenforschung,
+ * Mülheim an der Ruhr and FAccTs GmbH. ORCA is licensed by the Max-Planck-Institut für Kohlenforschung and FAccTs GmbH.
  *
- * Copyright (C) 2019 Sebastian Ehlert, Marvin Friede
+ * The inclusion of ORCA code in this file has been done with the explicit permission
+ * of the ORCA developers.
  *
- * cpp-d4 is free software: you can redistribute it and/or modify it under
- * the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * cpp-d4 is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with cpp-d4.  If not, see <https://www.gnu.org/licenses/>.
+ * For reuse or licensing of this code, please contact the ORCA team at the Max-Planck-Institut
+ * für Kohlenforschung (https://orcaforum.kofo.mpg.de/) or FAccTs GmbH (https://www.faccts.de/).
  */
 
 #pragma once