Clinical evaluation of the topical use of propolis in recurrent minor aphthous ulceration - Lotufo, Mônica Andrade; Lemos Júnior, Celso Augusto; Shimizu, Marcio Tsunezi; Cabral, Renata; Birman, Esther Goldenberg (Ciência Odontológica Brasiliera=Brazilian Dental Science, 2005)