It is almost impossible to keep all the listings current. A successful Internet travel requires patience and perseverance. Sites tend to lead to other sites which in turn lead to yet new ones. Each site has to be carefully examined before its usefulness can be determined since all sorts of valuable information may be hidden beneath the brief, uninformative labels buried within the various layers of a web. Perseverence however, may reward a user with unexpected gems.
Users have several options for finding desired materials.
If one knows the specific web site and has the URL, one can go there directly. A promising site should be examined carefuly, and all links followed. A thorough examination of a site takes time. One peels it like an onion, a layer at a time. To help the user distinguish them this guide will indicate by marking each with coloured balls.