diff --git a/code/DogSimulation.py b/code/DogSimulation.py
index daaa033..83cb143 100644
--- a/code/DogSimulation.py
+++ b/code/DogSimulation.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/LICENSE.txt b/code/LICENSE.txt
new file mode 100644
index 0000000..49beefe
--- /dev/null
+++ b/code/LICENSE.txt
@@ -0,0 +1,21 @@
+he MIT License (MIT)
+
+Copyright (c) 2015 Roger R. Labbe Jr
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
\ No newline at end of file
diff --git a/code/RobotLocalizationParticleFilter.py b/code/RobotLocalizationParticleFilter.py
index 1bdcc7d..6b4285a 100644
--- a/code/RobotLocalizationParticleFilter.py
+++ b/code/RobotLocalizationParticleFilter.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/adaptive_internal.py b/code/adaptive_internal.py
index ec861dc..9db517b 100644
--- a/code/adaptive_internal.py
+++ b/code/adaptive_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/book_format.py b/code/book_format.py
index c9a0467..2a76fed 100644
--- a/code/book_format.py
+++ b/code/book_format.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/book_plots.py b/code/book_plots.py
index 4408bc9..ab3b234 100644
--- a/code/book_plots.py
+++ b/code/book_plots.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/ekf_internal.py b/code/ekf_internal.py
index a5e9070..5ee508c 100644
--- a/code/ekf_internal.py
+++ b/code/ekf_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/gaussian_internal.py b/code/gaussian_internal.py
index b87682f..4428bbf 100644
--- a/code/gaussian_internal.py
+++ b/code/gaussian_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/gh_internal.py b/code/gh_internal.py
index 4a37437..486b78d 100644
--- a/code/gh_internal.py
+++ b/code/gh_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/gif_animate.py b/code/gif_animate.py
index ff51069..3559096 100644
--- a/code/gif_animate.py
+++ b/code/gif_animate.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/kf_design_internal.py b/code/kf_design_internal.py
index 76998b7..870a4e7 100644
--- a/code/kf_design_internal.py
+++ b/code/kf_design_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/kf_internal.py b/code/kf_internal.py
index 568b84c..b6996a2 100644
--- a/code/kf_internal.py
+++ b/code/kf_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/mkf_internal.py b/code/mkf_internal.py
index 2172842..5e90418 100644
--- a/code/mkf_internal.py
+++ b/code/mkf_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/nonlinear_internal.py b/code/nonlinear_internal.py
index 703ee71..4a23cec 100644
--- a/code/nonlinear_internal.py
+++ b/code/nonlinear_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/nonlinear_plots.py b/code/nonlinear_plots.py
index 9eb12e6..d450981 100644
--- a/code/nonlinear_plots.py
+++ b/code/nonlinear_plots.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/particle_filter.py b/code/particle_filter.py
index 6dcab3a..5fd3dd0 100644
--- a/code/particle_filter.py
+++ b/code/particle_filter.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/pf_internal.py b/code/pf_internal.py
index 36db871..c2c72f6 100644
--- a/code/pf_internal.py
+++ b/code/pf_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/smoothing_internal.py b/code/smoothing_internal.py
index ebef714..b449b34 100644
--- a/code/smoothing_internal.py
+++ b/code/smoothing_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """
 
diff --git a/code/ukf_internal.py b/code/ukf_internal.py
index 9d5e9b4..ffa722d 100644
--- a/code/ukf_internal.py
+++ b/code/ukf_internal.py
@@ -9,7 +9,7 @@ Kalman and Bayesian Filters in Python
 https://github.com/rlabbe/Kalman-and-Bayesian-Filters-in-Python
 
 
-This is licensed under an MIT license. See the readme.MD file
+This is licensed under an MIT license. See the LICENSE.txt file
 for more information.
 """