Resumen de Books in Brief.

• The article reviews books including "Agnes Martin" edited by Lynne Cooke and Karen Kelly, "Inventing Abstraction 1910-1925: How a Radical Idea Changed Art" edited by Leah Dickerman and "Robert Motherwell Paintings & Collages: A Catalogue Raisonné, 1941-1991" by Jack Flam, Katy Rogers and Tim Clifford.