.Lambek, Joachim (1969). "Deductive systems and categories II. Standard constructions and closed categories". Lecture Notes in Mathematics. Vol. 86. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 76–122. doi:10.1007/bfb0079385. ISBN978-3-540-04605-9. ISSN0075-8434.
.Lambek, Joachim (1969). "Deductive systems and categories II. Standard constructions and closed categories". Lecture Notes in Mathematics. Vol. 86. Berlin, Heidelberg: Springer Berlin Heidelberg. pp. 76–122. doi:10.1007/bfb0079385. ISBN978-3-540-04605-9. ISSN0075-8434.