SETI at 50.
D000846:Anniversaries and Special Events; D001256:Astronomy / Q000191:economics / Q000295:instrumentation / Q000639:trends; D002140:California; D018559:Exobiology / Q000266:history / Q000295:instrumentation / Q000379:methods* / Q000639:trends*; D049673:History, 20th Century; D049674:History, 21st Century; D011846:Radio Waves