ProQuest is an Ann Arbor, Michigan-based electronic publisher founded in 1938 as University Microfilms. It provides archives and databases of newspapers, periodicals, dissertations, and other sources. ProQuest's products include ProQuest NewsStand, a digital database of over 1,500 newspapers, and ProQuest Dissertations and Theses, the world's most comprehensive collection of graduate works. Over time, ProQuest has expanded its collections through acquisitions and now hosts over 90 million sources totaling more than 6 billion digital pages across history, science, arts and more.