Ayres, L. P. (1909). Laggards in our schools: A study of retardation and elimination in city school systems. Charities publication committee.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Ayres, Leonard Porter. Laggards in Our Schools: A Study of Retardation and Elimination in City School Systems. New York: Charities publication committee, 1909.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Ayres, Leonard Porter. Laggards in Our Schools: A Study of Retardation and Elimination in City School Systems. Charities publication committee, 1909.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.