Peter of Spain (Petrus Hispanus)  
   Life and work of 13th century logician and author of the Tractatus; from the Stanford Encyclopedia by Joke Spruyt.
   http://plato.stanford.edu/entries/peter-spain/

Excerpt from Peter of Spain  
   A brief passage from the Treatise on Distributions, in Joseph Mullally's translation. Discusses the problem of whether the negation of a statement makes it universal or renders it indeterminate.
   http://www.humnet.ucla.edu/humnet/phil/faculty/tparsons/phil107/p_spain.htm

Excerpts from the Commentary on Peter of Spain's Tractatus  
   Selections from this secondary work by Simon of Faversham, translated by John Longeway.
   http://uwp.edu/~longeway/peterspa.htm