Categorias ultradiofánticas - Leopoldo Román (1985)

Ultradiophantine Categories. - Leopoldo Román (Math. Log. Q., 1988)

Monoidal categories with natural numbers object. - Robert Paré; Leopoldo Román (Stud Logica, 1989)

An internal language for autonomous categories. - Ian Mackie; Leopoldo Román; Samson Abramsky (Appl. Categorical Struct., 1993)