Open Questions in Physics. German Electron-Synchrotron. A Research Centre of the Helmholtz Association. Updated March 2006 by JCB. Original by John Baez.
fnal.gov
quarknet.fnal.gov
„Units in particle physics”. Associate Teacher Institute Toolkit. Fermilab. 22 March 2002. Pristupljeno 13 February 2011.
stanford.edu
www2.slac.stanford.edu
„Special Relativity”. Virtual Visitor Center. SLAC. 15 June 2009. Arhivirano iz originala na datum 2008-08-28. Pristupljeno 13 February 2011.