Spate, O. H. K. (1979). "Chapter 2 The Alexandrine Bulls and the Treaty of Tordesillas". The Spanish Lake. Canberra: Australian National University Press. ISBN0-7081-0727-3.
books.google.com
Verzijl, Jan Hendrik Willem; W.P. Heere; J.P.S. Offerhaus (1979). International Law in Historical Perspective. Martinus Nijhoff. pp. 230–234, 237. ISBN978-90-286-0158-1.. Online, Google Books entry