Hunt's The Play of To-day.
Hale's Dramatists of To-day.
Henderson's George Bernard Shaw: His Life and Works, 2 vols.
Chesterton's George Bernard Shaw.
Weygandt's Irish Plays and Playwrights (excellent).
Krans's William Butler Yeats and the Irish Literary Revival.
Howe's J.M. Synge: A Critical Study.
Yeats's J.M. Synge and the Ireland of His Time (in The Cutting of an Agate, 1912).
Bickley's J.M. Synge and the Irish Dramatic Movement.
Elton's Living Irish Literature (in Modern Studies).