Orton, A. (1970). A cross-sectional study of the development of mathematical concept of function in secondary school children of average and above and average ability.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Orton, Anthony. A Cross-sectional Study of the Development of Mathematical Concept of Function in Secondary School Children of Average and Above and Average Ability. 1970.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Orton, Anthony. A Cross-sectional Study of the Development of Mathematical Concept of Function in Secondary School Children of Average and Above and Average Ability. 1970.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.