Westfall, S. (2013). the Hard-Edge Sign: Employing flat color and geometric form, hard-edge painters developed an abundance of styles and a rich if restrictive, esthetic whose legacy is still felt today. Art in America.

Westfall, Stephen. "The Hard-Edge Sign: Employing Flat Color and Geometric Form, Hard-edge Painters Developed an Abundance of Styles and a Rich If Restrictive, Esthetic Whose Legacy Is Still Felt Today." Art in America 2013.

Westfall, Stephen. "The Hard-Edge Sign: Employing Flat Color and Geometric Form, Hard-edge Painters Developed an Abundance of Styles and a Rich If Restrictive, Esthetic Whose Legacy Is Still Felt Today." Art in America, 2013.