APA (7th ed.) Citation

España, U. G. d. T. d., & Dukes, C. Letter.

Chicago Style (17th ed.) Citation

España, Unión General de Trabajadores de, and Charles Dukes. Letter.

MLA (8th ed.) Citation

España, Unión General de Trabajadores de, and Charles Dukes. Letter.

Warning: These citations may not always be 100% accurate.