“…κ 1 = κ 2 = 0, decouples operators H 2,3,6 , H 7-10 , and H 13,14 . The remaining operators form again an so(2,2) ⊂ so(4,2) Lie algebra which decomposes into two sets of operators acting separately from the right or from the left of the 033829-7 ,…”