
The images used in this example were released under "CC Attribution 2.0 Generic"
license, and are part of the public domain [1]

1.jpg: http://www.flickr.com/photos/fritography/4524444398/
2.jpg: http://www.flickr.com/photos/pargon/2461131176/
3.jpg: http://www.flickr.com/photos/usnavy/6219970385/
4.jpg: http://www.flickr.com/photos/butlerphotography/4201634265/

[1] http://creativecommons.org/licenses/by/2.0/deed.en
