MLA

Romero, Bernardo. Codex Romero: Course of Logic Taught in the Augustinian Convent of Mexico. 1596. https://collections.library.yale.edu/catalog/10622018.

APA, 6th edition

Romero, B. (1596). Codex Romero: Course of logic taught in the Augustinian convent of Mexico [Manuscripts, Renaissance Mexico 16th century, Medieval and Renaissance Manuscripts in Beinecke Library]. https://collections.library.yale.edu/catalog/10622018.