Origin and preservation of stratigraphically repeated, glacially striated surfaces in the Itararé subgroup (late paleozoic) in Palmeira, state of Paraná - Trosdtorf Júnior, Ivo; Rocha-Campos, A. C.; Tomio, Alexandre; Santos, Paulo Roberto dos; Canuto, José Roberto (Anais da Academia Brasileira de Ciências, 2001)