I'm trying to get to know the party and the movement behind it better but am having difficulty finding where to find the information.

With other parties there's a variety of biographies of key figures (like Brown At 10, Call me Dave, the Iron Chancellor and Coalition) and easily identifiable key philosophers (Marx, Rawls, Bentham and Beveridge for the Labour Party)(Mill, Keynes and Rawls again for liberals) but with the Greens I find a lot of this content hard to find.

I've read Caroline Lucas's "honourable friends?" and in Andrew Heywood's book "ideologies: an introduction" I read the chapter on ecologist, But that's about it. What else would recommend?