O'Keeffe, G., Cowart, J., & Hamilton, J. (1987). Georgia O'Keeffe, art and letters. National Gallery of Art.
Chicago Style (17th ed.) CitationO'Keeffe, Georgia, Jack Cowart, and Juan Hamilton. Georgia O'Keeffe, Art and Letters. Washington: National Gallery of Art, 1987.
MLA (9th ed.) CitationO'Keeffe, Georgia, et al. Georgia O'Keeffe, Art and Letters. National Gallery of Art, 1987.
Warning: These citations may not always be 100% accurate.