Most of the information available from this website is within the public domain. Public domain information on may be freely downloaded and reproduced for appropriate educational purposes - however, it is requested that in any subsequent use of this work, be given appropriate acknowledgment.

This site also contains some material, such as cartoons, photographs, graphs, graphics, text of journal articles and books that is copyright protected. For such material, the submitting authors or other copyright holders retain rights for reproduction or redistribution. All persons reproducing or redistributing this information are expected to contact the authors for permission for use.