Why might the Dewey Decimal system be the answer to a trivia question? At least some libraries are no longer using it. My university's library is in process of converting from the Dew Decimal system to the Library of Congress system of call numbers.

Apparently the Library of Congress system is much better than the Dewey Decimal system in organizing scientific writings. It also has another advantage. Have you ever looked for references just based on a Dewey Decimal number? Well the DD system apparently gives much different numbers to books, journals, and conference procedings on the same subject. The Library of Congress system allows for all three types of writings to be shelved together so long as they obviously cover the same subject.