Kessler, M. M., Thibeau, C. E., & Taliaferro, P. W. (1972). NFEC directory of environmental information sources (2nd ed.). Boston, MA: The National Foundation for Environmental Control.
Παραπομπή Chicago StyleKessler, Myer M., Charles E. Thibeau, and Peter W. Taliaferro. NFEC Directory of Environmental Information Sources. 2nd ed. Boston, MA: The National Foundation for Environmental Control, 1972.
Παραπομπή MLAKessler, Myer M., Charles E. Thibeau, and Peter W. Taliaferro. NFEC Directory of Environmental Information Sources. 2nd ed. Boston, MA: The National Foundation for Environmental Control, 1972.
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