*{{Citationchú thích |first=Howard |last=Georgi |title=Lie algebras in particle physics |year=1999 |location= |publisher=Perseus Books Group |isbn=0738202339 }}.
*{{Citationchú thích |first=David J. |last=Griffiths |title=Introduction to Elementary Particles |year=1987 |publisher=John Wiley & Sons |location=New York |isbn=0471603864 }}.
*{{Citationchú thích |first=J. Richard |last=Christman |url=http://35.9.69.219/home/modules/pdf_modules/m283.pdf |title=Color and Charm |year=2001 |work=[http://www.physnet.org Project PHYSNET] document MISN-0-283 }}.
*{{Citationchú thích |first=Stephen |last=Hawking |title=A Brief History of Time |year=1998 |location= |publisher=Bantam Dell Publishing Group |isbn=9780553109535 }}.
*{{Citationchú thích |first=Frank |last=Close |title=The New Cosmic Onion |year=2007 |location= |publisher=Taylor & Francis |isbn=1584887982 }}.