Good researchers cannot limit themselves to only using online search boxes.
Q: Why bother with looking through the books stacks in the library when you have access to so much online?
A: Serendipity - "finding valuable or agreeable things not sought for"
In order to do "progressive refinement" you have to know in advance which exact words will produce the refinement you seek, and it is precisely that knowledge that we lack when we are moving around in unfamiliar subject areas.
-- Thomas Mann from The Oxford Guide to Library Research (4th ed.)
One of our databases has the full text for Time Magazine back to 1923, but it does not include everything - for example it leaves out all of the advertising. Browsing though our bound volumes of Time Magazine from 1944 to look at advertising during the war can uncover lots of interesting themes and angles that could never be anticipated in advance.
An unbroken descriptive chronology of terrorists acts from 1968 though 2012 which is NOT available online.
Antonio Vivaldi wrote 530 concertos and sonatas. Here they all are on our shelves. No need to waste time searching or printing.
Twenty volumes documenting the cleanup of the nuclear waste dump 20 minutes from Morehead. Maybe copies exists in the vaults at the EPA (and maybe not).
A researcher MUST browse through the primary source material to be able to see what is there.
Primary sources housed in archives and manuscript collections (or even ones that have been digitized and are online) are often:
