“…2) Fink [9] proved that for a periodic system, the exponential uniform asymptotic stability implies the existence of bounded solutions, thus it follows the existence of periodic solutions, and he conjectured that for an almost periodic system the exponential uniform asymptotic stability implies the existence of almost periodic solutions, which was proved by Lin [15] when the system satisfies the Lipschitz condition and is uniformly asymptotically stable. For some periodic solution theory, see [5,4,11,7,2] and references therein.…”