Avoid upper case letters in your searches as capitals must match exactly, whereas lower case will match upper and lower case. Internet directories are far less comprehensive than search engines, but because the entries are hand-picked, they reflect some measure of quality. These directories start with a small list of subject headings which lead down through a hierarchical index. The deeper you go, the more specifically defined are the pages that are listed. Most search engine sites also have this sort of directory guide.
Subject gateways are more specific than global engines.
They contain databases of Web sites for a particular discipline. The information usually includes a brief description of each resource, some keywords and a link to the relevant site. Subject gateways are common for academic disciplines. The advantage that these gateways have over search engines is that they list only reliable, high content sites and the smaller number of catalogued sites make searching less daunting. Many other Web sites also list more informal links to related resources.