“…The former can be employed to discuss local stability of the synchronous state, and the latter can be used to explore global stability of the synchronous state. Up to now, dozens of different types of synchronization states have been proposed such as complete synchronization [14], cluster synchronization [15,16], lag synchronization [17,18], projection synchronization [19,20], and outer synchronization [21][22][23]. Thereinto, outer synchronization has attracted many researchers' interest, which describes the synchronization 2 Mathematical Problems in Engineering between two or more networks.…”