Crowley, W. R. (1997). Chemicals on the Internet: A directory of industry sites. Gulf Pub. Co.
Lua i Stíl Chicago (17ú heag.)Crowley, William R. Chemicals on the Internet: A Directory of Industry Sites. Houston, Tex: Gulf Pub. Co, 1997.
Lua MLA (9ú heag.)Crowley, William R. Chemicals on the Internet: A Directory of Industry Sites. Gulf Pub. Co, 1997.
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