Check out this archive with literally hundreds of links on nationalism. Its purpose is scholarly rather than inflammatory. The links range from high-level political theory analyses to organizations promoting atrocious pseudo-history and racism. Many of them are just plain fascinating, ranging from Dutch claims to have invented printing to Italian irridentism in Dalmatia to invented "Irish" names used by the diaspora in America to an exhaustive list of the nearly 100 "genocides" the Assyrians have suffered since 612 BC.
There is something in here to offend absolutely everybody, so check it out. You are likely to learn a great deal, a lot of which is probably wrong; you yourself must be the judge of the credibility of a linked source.