Figure 1.
Chemical formulas of some 3-, 4- and 5-ring PAHs [http://www.chemport.ru/].
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.