diff --git a/doc/Interrupts.txt b/doc/Interrupts.txt
index ab87a90..2d7e521 100644
--- a/doc/Interrupts.txt
+++ b/doc/Interrupts.txt
@@ -1,3 +1,22 @@
+doc/Interrupts.txt
+Copyright (C) 2015  Mikael Pettersson
+
+This file is part of pdp10-tools.
+
+pdp10-tools is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+pdp10-tools 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with pdp10-tools.  If not, see <http://www.gnu.org/licenses/>.
+
+
 PDP10 Interrupt Architecture
 ============================
 
diff --git a/doc/Paging.txt b/doc/Paging.txt
index 8ddc78b..1469fe5 100644
--- a/doc/Paging.txt
+++ b/doc/Paging.txt
@@ -1,3 +1,22 @@
+doc/Paging.txt
+Copyright (C) 2015  Mikael Pettersson
+
+This file is part of pdp10-tools.
+
+pdp10-tools is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+pdp10-tools 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with pdp10-tools.  If not, see <http://www.gnu.org/licenses/>.
+
+
 PDP10 Paging
 ============
 
diff --git a/doc/Timers.txt b/doc/Timers.txt
index 8d7e07e..eb12ed3 100644
--- a/doc/Timers.txt
+++ b/doc/Timers.txt
@@ -1,3 +1,22 @@
+doc/Timers.txt
+Copyright (C) 2015  Mikael Pettersson
+
+This file is part of pdp10-tools.
+
+pdp10-tools is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+pdp10-tools 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with pdp10-tools.  If not, see <http://www.gnu.org/licenses/>.
+
+
 PDP10 Timers
 ============