978-0-7190-3347-6) LeoXIII, Rerum novarum, 3. LeoXIII, Rerum novarum, 6. LeoXIII, Rerum novarum, 46. LeoXIII, Rerum novarum, 42. LeoXIII, Rerum novarum, 45. Leo XIII
Britannica | LeoXIII (بالإنجليزية), QID:Q5375741 Brockhaus Enzyklopädie | Leo (LeoXIII.) (بالألمانية), QID:Q237227 Gran Enciclopèdia Catalana | Lleó XIII (بالكتالونية)
"LeoXIII and His Successors". The Triple Crown: An Account of the Papal Conclaves. London: Sidgwick & Jackson. Hittinger، Russell (2006). "Pope Leo XIII"