A subset of the total collection of books and documents in the NLM Literature Archive (NLM LitArch), accessible through the Bookshelf website, are available through the NLM LitArch Open Access subset. Contents in the NLM LitArch Open Access subset generally include works which are in the public domain, works which are available under a Creative Commons or similar license, and works whose authors or publishers have explicitly agreed to the terms of the NLM LitArch Open Access subset. Except for public domain works, works in the NLM LitArch Open Access subset are still protected by copyright, but are made available under a Creative Commons or similar license that generally allows more liberal redistribution and reuse than a traditional copyrighted work. The license terms are not the same for each work. Read the license text which is available with each downloadable file to determine terms of use.

Please note the following regarding the NLM LitArch Open Access subset:

• Most books and documents available in NLM LitArch and accessible via the NLM Bookshelf site are subject to traditional copyright restrictions, and are not part of this subset. Read the Bookshelf Copyright Statement for more information.
• The NLM LitArch FTP service is the only service that may be used for automated downloading of content from this open access subset.
• Systematic retrieval (bulk downloading) of content through any other automated process is prohibited, even if you are only retrieving documents from this subset.
• Some publishers and content providers use the term “open access” for books and reports that are available for free at the time of publication, but they are still subject to the same copyright restrictions. Such documents are not part of the Bookshelf Open Access subset.

Use the FTP service to download the complete sets of files for books and documents in this subset. Each downloadable file typically consists of the following data file types: XML, images, and PDF.