Internet Archive - This non-profit partnership of over 600 institutions, foundations, and government agencies has been building a digital library of Internet sites and other cultural artifacts in digital form since 1996. Like a paper library, they provide free access to researchers, historians, scholars, the print disabled, and the general public to digital versions of millions of published works including:
Try this search which uses the Subject Heading for the war rather than a keyword approach: World War 1914 . You can also use keyword/free text searching with the usual synonyms: World War I, First World War, Great War, World War One, World War 1.
REMEMBER #1: when searching large, multi-subject sources, always link any topical phrase, e.g. pacifist, with a subject term for THIS war
REMEMBER #2: Internet Archive holdings span several hundred years and will be a mix of secondary and primary sources. Use the publication date filters in the left-hand frame to limit material to the time period of the war
REMEMBER #3: Secondary source texts which are still under copyright can be borrowed from The Open Library portion of the Internet Archive. Just like Adams Library, those items can only be borrowed by one person at a time and are unavailable to others until "returned" by the borrower.
NARA Investigative Archivist, Mitchell Yokelson, is an internationally renowned expert in military history, particularly of World War I. Consult these two overview articles written by him for NARA's Prologue magazine:
“America enters the Great War” Spring 2017, Vol. 49, No. 1
"They Answered the Call:Military Service in the United States Army During World War I, 1917–1919" Fall 1998, Vol. 30, No. 3
National Museum of American History (Smithsonian) - myriad collections with World War I materials. A search using "World War I" brings many of them together, but REMEMBER to use the synonyms, e.g. "First world war" as well.
Among other activities, the Commission serves as a clearinghouse for information about the centennial, including links to the 35 states which developed their own World War I commemoration sites.
Small but amazing in the sheer number of audio recordings (mostly musical numbers) from the World War I period, this archive can be searched using the standard LCSH heading "World War, 1914-1918" as well as additional keywords such as names of dedicatees, performers, and places.
World War One (British Library) - this curated presentation of British materials in the Europeana 1914-1918 collection (see the Primary sources TAB of this LibGuide) includes original documents along with commentary, explanatory essays and interviewsabout them with leading historians and social scientists.