adaviel (1189751) writes "LORAN (Long Range Aids to Navigation) is an electronic navigation system using low-frequency radio, used by many boaters (including me) before GPS. It has an approximately 200m accuracy and is a functional replacement in case GPS fails or the US implements selective availability in time of war. The US Coast Guard intends to turn it off starting February 8." Link to Original Source
The best book on programming for the layman is "Alice in Wonderland";
but that's because it's the best book on anything for the layman.