Dalkey, Norman; Helmer, Olaf (1963). “An Experimental Application of the Delphi Method to the use of experts”. Management Science9 (3): 458–467. doi:10.1287/mnsc.9.3.458. hdl:2027/inu.30000029301680.
Basu, Shankar; Roger G. Schroeder (May 1977). “Incorporating Judgments in Sales Forecasts: Application of the Delphi Method at American Hoist & Derrick”. Interfaces7 (3): 18–27. doi:10.1287/inte.7.3.18.
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Dalkey, Norman; Helmer, Olaf (1963). “An Experimental Application of the Delphi Method to the use of experts”. Management Science9 (3): 458–467. doi:10.1287/mnsc.9.3.458. hdl:2027/inu.30000029301680.
"JVTE v15n2: The Modified Delphi Technique - A Rotational Modification," Journal of Vocational and Technical Education, Volume 15 Number 2, Spring 1999, web: VT-edu-JVTE-v15n2: of Delphi Technique developed by Olaf Helmer and Norman Dalkey.