Small Question

While I'm in the midst of doing stuff other than blogging...

I seem to recall a series of books from childhood with a character who solved mysteries. He (or she) used the slogan "No question too small." I've run a Google search on that phrase, but a lot of other places seem to use it as well. Does anyone out there have an inkling of what book or books I might be remembering?

(Edited To Add: It's from Encyclopedia Brown. Thanks to all!)