“…The reader is referred to [1,4,5,7,8,[11][12][13][14]32] and references therein for some examples and applications. The problem of the existence of solutions of functional differential equations with state-dependent delay has been treated recently in [2,[16][17][18][19][20]25]. The literature related to second order nonlinear systems with state-dependent delay is not vast, to our knowledge, in the recent works [6,15].…”