Further clarifications of "Necessary and sufficient stability condition   of fractional-order interval linear systems"
  This technical report replies to the comments of [2] in detail, and corrects a possible mis-interpretation of [1] in terms of the conventional robust stability concept. After defining the robust stability and quadratic stability concepts, it will be more clearly described that the condition established in [1] can be considered an exact condition for the quadratic stability of fractional-order interval systems. 
Hyo-Sung Ahn, Young-Hun Lim, Kwang-Kyo Oh, and YangQuan Chen
math.OC