The Pythagorean Sourcebook and Library: An Anthology of Ancient Writings Which Relate to Pythagoras and Pythagorean Philosophy, compiled and translated by Kenneth Sylvan Guthrie, edited and introduced by David Fideler, a 1987 paperback from Phanes Press, is part of the collection at the Reading Room.
“Pythagoras (fl. 500 B.C.E.), the first man to call himself a philosopher, was both a brilliant mathematician and spiritual teacher. This anthology is the largest collection of Pythagorean writings ever to appear in the English language. It contains the four ancient biographies of Pythagoras and over twenty-five Pythagorean and Neopythagorean writings from the classical and Hellenistic periods. The Pythagorean ethical and political tractates are especially interesting, for they are based on the premise that the universal principles of Harmony, Proportion, and and Justice govern the physical cosmos, and these writings show how individuals and societies alike attain their peak of excellence when informed by these same principles. Indexed, illustrated, with appendices and an extensive bibliography, this work also contains an introductory essay by David Fideler.” — back cover