Directories, on the other hand, are developed by human researchers, who review and categorize each site. Directories are more selective than search engines. Use a directory when you are looking for information about broad topics. Just as library materials have clues as to their accuracy, so do materials on the Internet. Cite the Internet resources you use.
Websites are the obvious resources.
But email is also a way to communicate with people, and some websites will even put you in touch with experts in various fields.