We follow CMS guidance on the usage of en dashes. See CMS 6.78–6.81 for rules regarding the use of en dashes.
Examples: 1998–1999; July 2005–June 2007; $325–$999
Use an en dash to indicate joint research or development.
Examples: Black–Scholes model; the Berry–Dreman research
Use an en dash for acts of Congress.
Examples: Taft–Hartley Act; Glass–Steagall Act