Catholic Encyclopedia: Pythagoras and Pythagoreanism: Entry by William Turner. Concise summary of doctrines attributed to Pythagoras.
Pythagoreanism: Information about the arguments in this book written by Eric Steinhart, including overview and chapter abstracts. Interprets "pythagoreanism" in modern terms, as a philosophy radically opposed to Platonism.
Pythagoreanism: Detailed essay on the development and legacy of this school.
The Mystica: Pythagoreanism: Digest of this school's teachings and its relation to Platonism.