A few years ago (2010), I contributed to a big old textbook about Modern European and American drama published by Routledge under the title The Routledge Drama Anthology and Sourcebook: From Modernism to Contemporary Performance. I handled the section on Naturalism and Symbolism, offering a long introduction and overview to these movements and also translating Maeterlinck's Interior and 'Tragedy in Everyday Life' and Pierre Quillard's 'On the Complete Pointlessness of Accurate Staging' . Well it's gone into a second edition. My section hasn't changed but much of the rest has. And it's got a slightly snappier title. If you want a one-volume guide to some of the most exciting movements in experimental western theatre, you can't do better.
Gale, Maggie B., John Deeney, Dan Rebellato, and Carl Lavery. The Routledge Drama Anthology: From Modernism to Contemporary Performance. 2nd ed. Abingdon: Routledge, 2016.