Who said that?

While searching Google for a quotation searcher I stumbled upon http://www.quotationspage.com/, a free quote searcher. On my first visit my pop-up blocker alerted me of 2 pop-ups, but other than that i found the site satisfactory. I tried "no matter how", and it returned the exact quote i was searching for:

...when you have eliminated the impossible, whatever remains, however improbable, must be the truth.

Sir Arthur Conan Doyle (1859 - 1930), (Sherlock Holmes)