Government information at NLM Web sites is in the public domain. Public domain information may be freely distributed and copied, but it is requested that in any subsequent use the National Library of Medicine (NLM) be given appropriate acknowledgement. When using NLM Web sites, you may encounter documents, illustrations, photographs, or other information resources contributed or licensed by private individuals, companies, or organizations that may be protected by U.S. and foreign copyright laws. Transmission or reproduction of protected items beyond that allowed by fair use as defined in the copyright laws requires the written permission of the copyright owners. Specific NLM Web sites containing protected information provide additional notification of conditions associated with its use.
Information contributed by DOCLINE participants is covered by the DOCLINE Privacy Policy. Institution directory information that is publically available is accessible from the Network of the National Library of Medicine (NNLM) Members Directory.
DOCLINE participants are required to comply with copyright laws governing their country or legal jurisdiction in providing interlibrary loan and document delivery. Materials outside of what is allowed under Sections 107-108 of the U.S. Code would require payment to the publisher or other copyright holder. Libraries utilizing electronic journals may additionally be bound by publisher license agreements. For more information on copyright, we suggest: United States Copyright Office, CONTU Guidelines.
Disclaimers
Liability: For documents and software available from this server, the U.S. Government does not warrant or assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed.
Endorsement: NLM does not endorse or recommend any commercial products, processes, or services. The views and opinions of authors expressed on NLM Web sites do not necessarily state or reflect those of the U.S. Government, and they may not be used for advertising or product endorsement purposes.
Pop-Up Advertisements: When visiting our Web site, your Web browser may produce pop-up advertisements. These advertisements were most likely produced by other Web sites you visited or by third party software installed on your computer. The National Library of Medicine does not endorse or recommend products or services for which you may view a pop-up advertisement on your computer screen while visiting our site.
External Links: Some NLM sites may provide links to other Internet sites only for the convenience of World Wide Web users. NLM is not responsible for the availability or content of these external sites, nor does NLM endorse, warrant or guarantee the products, services or information described or offered at these other Internet sites. It is the responsibility of the user to examine the copyright and licensing restrictions of linked pages and to secure all necessary permission. Users cannot assume that the external sites will abide by the same provisions as the NLM Privacy Policy.
Medical Information: It is not the intention of NLM to provide specific medical advice, but rather to provide users with information to better understand their health and their diagnosed disorders. Specific medical advice will not be provided, and NLM urges you to consult with a qualified physician for diagnosis and for answers to your personal questions.
License Notice: For production and display of GIF images, this site uses Unisys patent No. 4,558,302 and/or foreign counterparts, which is licensed by Unisys for use on this site as a public service.
Last Reviewed: August 17, 2020