Ketchum, M. S., & Draffin, J. O. (1932). Strength of light I beams: A report of an investigation conducted by the Engineering Experiment Station, University of Illinois in coöperation with Jones and Laughlin Steel Corporation. University of Illinois.
توثيق أسلوب شيكاغو (الطبعة السابعة عشر)Ketchum, Milo S., و Jasper Owen Draffin. Strength of Light I Beams: A Report of an Investigation Conducted by the Engineering Experiment Station, University of Illinois in Coöperation with Jones and Laughlin Steel Corporation. Urbana, Ill.: University of Illinois, 1932.
توثيق جمعية اللغة المعاصرة MLA (الطبعة الثامنة)Ketchum, Milo S., و Jasper Owen Draffin. Strength of Light I Beams: A Report of an Investigation Conducted by the Engineering Experiment Station, University of Illinois in Coöperation with Jones and Laughlin Steel Corporation. University of Illinois, 1932.