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WikiPedia: Kẻ_thả_chất_độc_điên_cuồng_ở_Mattoon http://www.encyclopedia.com/doc/1G1-88826374.html http://www.prairieghosts.com/gasser.html http://www.time.com/time/magazine/article/0,9171,7... http://www.eiu.edu/~localite/coles/mattoon/gasser/... http://www.eiu.edu/~localite/coles/mattoon/gasser/... http://www.eiu.edu/~localite/coles/mattoon/gasser/... http://www.eiu.edu/~localite/coles/mattoon/gasser/... http://www.eiu.edu/~localite/coles/mattoon/gasser/... http://www.eiu.edu/~localite/coles/mattoon/gasser/... //doi.org/10.1037%2Fh0062339