“…where X SLJ is any quantity depending on S, L and J, enables one to deal with the coupling of angular momenta L and S avoiding the use of coefficients of fractional parentage. One has ḡe = S,L,J L ′ ,J ′ Q(S, L ′ ) g e (S, L, J, L ′ , J ′ ) ǫ(L, L ′ , J, J ′ ), (54) where ǫ(L, L ′ , J, J ′ ) stands for the selection rules: L ′ = L, L − 1 or L + 1 avoiding L ′ = L = 0 and J ′ = J, J − 1 or J + 1 avoiding J ′ = J = 0. One has…”