John XXIII, P. (1960). On the use of leisure time: Letter to Social Week of Italian Catholics, September 20, 1959. National Catholic Welfare Conference.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)John XXIII, Pope. On the Use of Leisure Time: Letter to Social Week of Italian Catholics, September 20, 1959. Washington, D.C.: National Catholic Welfare Conference, 1960.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)John XXIII, Pope. On the Use of Leisure Time: Letter to Social Week of Italian Catholics, September 20, 1959. National Catholic Welfare Conference, 1960.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.