Leo XIII, P. (1940). Rerum Novarum: Encyclical Letter of Pope Leo XIII on the Condition of Labor. New York.
Dyfyniad Arddull ChicagoLeo XIII, Pope. Rerum Novarum: Encyclical Letter of Pope Leo XIII on the Condition of Labor. New York, 1940.
Dyfyniad MLALeo XIII, Pope. Rerum Novarum: Encyclical Letter of Pope Leo XIII on the Condition of Labor. New York, 1940.
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