This archive provides access to older editions of textbooks hosted on this website for purposes of reference. Because medicine is an ever-changing science, we include only the most recent previous edition of each title. As new research and clinical experience broaden our knowledge, changes in treatment and drug therapy are required. The authors of these works have checked with sources believed to be reliable in their efforts to provide information that is complete and generally in accord with the standards accepted at the time of publication. However, in the view of the possibility of human error or changes in medical science, neither the authors nor the publisher nor any other party who has been involved in the preparation or publication of this work warrants that the information contained herein is in every respect accurate or complete, and they disclaim all responsibility for any errors or omissions or for the results obtained from use of the information contained in these works. Readers are encouraged to confirm the information contained herein with other resources.