School Mathematics Study Group & Schaaf, W. L. (1967). Nature and history of Pi. Leland Stanford Junior University.
Lua i Stíl Chicago (17ú heag.)School Mathematics Study Group agus William L. Schaaf. Nature and History of Pi. Stanford, CA: Leland Stanford Junior University, 1967.
Lua MLA (9ú heag.)School Mathematics Study Group agus William L. Schaaf. Nature and History of Pi. Leland Stanford Junior University, 1967.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.