New sources!

I found these because Lowe mentioned Angela McRobbie at the end of the "Tween Scene" article:

The Subcultures Reader
Chapter 13: "Girls and Subcultures"
by Angela McRobbie and Jenny Garber
(link)

Feminism and Youth Culture : From "Jackie" to "Just Seventeen"
By Angela McRobbie
(link)

Feminism and Cultural Studies
Chapter 3: "Shut up and Dance: Youth Culture and Changing Modes of Feminitity"
by Angela McRobbie

Although these seem like great sources, and a good historical perspective, I don't think I'm going to focus too much on feminism in my piece.