Agatha Christie (and other mystery writers) in Wikipedia
Keep in mind that:
A lot of useful information is not freely available on the web. It is proprietary, meaning someone--an author, a publisher, or institution--owns the information. More about the Invisible Web.
You need to critically analyze and evaluate the information you intend to use.
There are still BOOKS in the Library. And other print and analog resources that do not exist on the Web.