References published by the Real Academia Española (RAE) will be used to develop the Spanish grammar section of the EN/ES Editorial Manual because the academy is recognized throughout the Spanish-speaking world. The Diccionario de la lengua española, RAE’s dictionary, and the Diccionario panhispánico de dudas, which provides explanations to doubts of Spanish usage, are free to use on RAE’s website.

The other three references, Nueva Gramática de la lengua española, which offers descriptive interpretations of Spanish grammar, Ortografía de la lengua española, which describes the rules of Spanish orthography, and El Buen uso de español, which offers grammar and orthography rules written in simple language, are only available in print.