http://www.europeana-collections-1914-1918.eu/

Europeana Collections 1914-1918 will create by 2014 – the centenary of the outbreak of the First World War – a substantial digital collection of material from national library collections of ten libraries and other partners in eight countries that found themselves on different sides of the historic conflict.

http://www.nationalarchives.gov.uk/pathways/firstworldwar/index.htm

This exhibition makes available an online selection of unique and richly varied source material on the First World War, set in its historical context. It provides resources for a wide variety of adult learners in the field of modern history.

The exhibition draws on historical documents, film and sound available in Britain's National Archives and one of its leading museums. It starts from, but is not limited to, a British perspective on the war, and also aims to create a wider understanding of the global nature of the conflict and the profound consequences that resulted from it - consequences which, in areas such as the Balkans and Palestine, are still being felt today.

http://www.oucs.ox.ac.uk/ww1lit/

The First World War Poetry Digital Archive is an online repository of over 7000 items of text, images, audio, and video for teaching, learning, and research.

The heart of the archive consists of collections of highly valued primary material from major poets of the period, including Wilfred Owen, Isaac Rosenberg, Robert Graves, Vera Brittain, and Edward Thomas. This is supplemented by a comprehensive range of multimedia artefacts from the Imperial War Museum, a separate archive of over 6,500 items contributed by the general public, and a set of specially developed educational resources. 

• Think about who would own such documents: libraries, archives, museums, etc., and look through their websites.

• Use the term "primary source" in your search string when searching the WWW.

• Don't forget the McQuade library's print collection.  Before the internet, primary sources were reproduced and printed in books.