The text of this book is released under the following license:
| Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License."
GFDL GNU Free Documentation License
Some initial text and contributions are derived from the US Department of Labor. All US Government published resources are released into the Public Domain.