National Science and Technology Council (U.S.). Air Quality Research Subcommittee. Preliminary Survey of Air Quality and Related Health Studies Conducted in the Vicinity of Ground Zero, text, December 2002; (https://digital.library.unt.edu/ark:/67531/metadc25970/m1/1/: accessed December 13, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .