WCommunication with extraterrestrial intelligence
WA Simple Response to an Elemental Message
WBracewell probe
WBreakthrough Listen
WCosmic Call
WDrake equation
WFrank Drake
WAnn Druyan
WYvan Dutil
WExtraterrestrial life
WHans Freudenthal
WGauss's Pythagorean right triangle proposal
WNikolai Kardashev
WLone Signal
WMessage in a bottle
WMorse Message (1962)
WNIROSETI
WAlexander Ollongren
WPioneer plaque
WCarl Sagan
WIosif Shklovsky
WTeen Age Message
WTime capsule
WDouglas Vakoch
WVoyager Golden Record
WAlexander Zaitsev (astronomer)