I wrote an effort post a while back about nationalism that you might be interested in. It has a few academic sources as well.

Personally, I think a lot of leftists could benefit from reading more deeply into nationalism. There are a lot people, even here, who are staunch anticapitalists but still accept that nations are a natural phenomenon and the nation-state the natural basic political unit. This is a testament to the way in which nationalism, even more than capitalism, with which it is deeply intertwined, has made itself invisible as ideology.

This is from two years ago