International Union of Geological Sciences. International Subcommission on Stratigraphic Classification & Hedberg, H. D. (1976). International stratigraphic guide: A guide to stratigraphic classification, terminology, and procedure. Wiley.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)International Union of Geological Sciences. International Subcommission on Stratigraphic Classification و Hollis Dow Hedberg. International Stratigraphic Guide: A Guide to Stratigraphic Classification, Terminology, and Procedure. New York: Wiley, 1976.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)International Union of Geological Sciences. International Subcommission on Stratigraphic Classification و Hollis Dow Hedberg. International Stratigraphic Guide: A Guide to Stratigraphic Classification, Terminology, and Procedure. Wiley, 1976.