There is an illustration of St. John Stone by János Hajnal in "Il Fascino di Dio: Profili de Agiografia Agostiniana" by Fernando Rojo Martínez, O.S.A.
The book "Il Fascino di Dio: Profili de Agiografia Agostiniana" by Fernando Rojo Martínez, O.S.A., contains an illustration of St. John Stone created by János Hajnal.