&Eta;&chi;&#974; &Epsilon;&nu;&#972;&sigmaf; &Tau;&rho;&alpha;&gamma;&omicron;&upsilon;&delta;&iota;&omicron;&#973; by A. L Butcher, &Alpha;&theta;&alpha;&nu;&alpha;&sigma;&#943;&alpha; &Sigma;&epsilon;&rho;&epsilon;&pi;&#943;&sigma;&omicron;&upsilon;