http://www.departedflights.com, Official Airline Guide (OAG) editions: April 1, 1974; November 15, 1979; April 1, 1981; February 15, 1985; December 15, 1989; October 1, 1991; April 2, 1995; June 1, 1999
http://www.departedflights.com, Official Airline Guide (OAG) editions: November 15, 1979; April 1, 1981; February 15, 1985; December 15, 1989; October 1, 1991; April 2, 1995; June 1, 1999