Columbia University
Intensive Organic Chemistry: Arenes and Aromaticity
Lecture notes from Chapter on Arenes & Aromaticity. Can be downloaded using Adobe Acrobat.
Wikimedia
Wikipedia: Aromatic Hydrocarbon
A nice, concise summary of aromatic hydrocarbons is found here at Wikipedia encyclopedia. The article tells what they are, what Huckel's Rule is, gives information on aromatic bonding, and gives a couple of examples of aromatic...