“…In [5], instead of considering the two sets T A and N A , the authors have considered much smaller subsets T G and N G , where G is a non-central normal subgroup of A × . The main results of [5] demonstrates that the sets T G and N G are too big in the whole A; that is, if we impose suitable conditions on T G ∪ N G , then the algebraic structure of the whole ring A is effected. More precisely, it was shown that if A is a division ring and T G ∪ N G is commutative, then A is a quaternion division algebra over Z(A) and ⋆ is of the symplectic type (see [5,Theorem 5.5]).…”