MLA

Ochoa Carrillo, Antonio, 1811-1883. Juárez, Benito. Autograph letter, signed: El Paso del Norte, to Antonio Ochoa Carrillo. Box 1, folder 52. 1866 May 26. https://collections.library.yale.edu/catalog/32319995.

APA, 6th edition

Ochoa Carrillo, Antonio, 1811-1883. (["Box 1, folder 52"])(1866 May 26)[Juárez, Benito. Autograph letter, signed: El Paso del Norte, to Antonio Ochoa Carrillo]. https://collections.library.yale.edu/catalog/32319995.