Speusippus
Links
Speusippus
http://plato.stanford.edu/entries/speusippus/
Article from the Stanford Encyclopedia of Philosophy by Russell Dancy. Reviews in depth what is known about his life and doctrines.
The Unwritten Doctrines: Plato's Answer to Speusippus
http://www2.kenyon.edu/people/pepplej/
An essay by John Pepple, arguing that Plato's later works include a response to Speusippus' rejection of the Platonic forms.
Speusippus
http://www.bartleby.com/65/sp/Speusipp.html
Brief entry from the 2001 Columbia Encyclopedia.