Equation Icon  √ -- √ -- √ -- -- uret = 2uB = 2G = τ − --2ξi(τ)Y01i(ζ,ζ ), (146 ) √ -- 2 2 i 0 -- τ = uret +----ξ(uret)Y1i(ζ,ζ). (147 ) 2