http://ru.wikipedia.org/wiki/Внеземная_цивилизация#.D0.9F.D0.B0.D1.80.D0.B0.D0.B4.D0.BE.D0.BA.D1.81_.C2.AB.D0.92.D0.B5.D0.BB.D0.B8.D0.BA.D0.BE.D0.B3.D0.BE_.D0.9C.D0.BE.D0.BB.D1.87.D0.B0.D0.BD.D0.B8.D1.8F.C2.BB