When Google doesn't get it ... there are areas when a different search approach can save time. Searching for historical papers can be made more efficient by using these archives, listed by Mark Shelton at Brown University. Care to add any others?

• The Smithsonian/NASA Astrophysics Historical Literature Scans
• DIEPER: Digitised European Periodicals
• Gottinger Digitalisierungs-Zentrum
• Gallica: la bibliotheque numerique