Elfring, T. (1988). Service sector employment in advanced economies: A comparative analysis of its implications for economic growth. Avebury.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Elfring, Tom. Service Sector Employment in Advanced Economies: A Comparative Analysis of Its Implications for Economic Growth. Aldershot, Hants, England ; Brookfield, Vt., USA: Avebury, 1988.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Elfring, Tom. Service Sector Employment in Advanced Economies: A Comparative Analysis of Its Implications for Economic Growth. Avebury, 1988.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.