Complex sentence: The Roman Catholic Church has not issued a ruling in the authenticity of the Marian apparition, but refers to a private audience granted by Pope Pius XII to Pierina Guilli on 9 August 1951 at Castel Gandolfo.
Split into simpler sentences: The Roman Catholic Church has not issued a ruling on the authenticity of the Marian apparition. It refers to a private audience granted by Pope Pius XII to Pierina Guilli on 9 August 1951 at Castel Gandolfo.