When first compiling this source in early 1997, search engines found many links to many propagation pages. We found no original material excepting what we list below. Virtually all URLs were traced back to the sources we found and include below. These sites or pages should help . A number of universities and colleges do research on the effects of solar radiation on the earth .
Some government agencies have a lot of material and statistics.
Miscellaneous These pages are constructed by non-government organizations, individuals, and small companies. Typically, data is organized and presented in ways not necessarily found on the governmental and educational institution pages. Also see the note below . Software The software products' developers include government issue, commercial vendors, radio amateurs and shortwave listeners. Note that we have not evaluated these products.