“…After that, by constructing some suitable Lyapunov functional, they also obtained a set of sufficient conditions which ensure the global attractivity of the positive periodic solution. After the works of [1,13,14,21,24,27,28], many scholars ( [4,7,8,12,16,23,31,32,[34][35][36]) done works on this direction. For example, Chen [12] further incorporated the feedback control variables to the system (1.3) and investigated the persistent property of the system.…”