"World airline survey". Flight International. 91 (3031): 549, at 595. 13 April 1967. Archived from the original on 28 June 2017. Retrieved 21 February 2022.
Stroud, Michael (21 March 1974). "World airline directory". Flight International. 105 (3393): 1, at 58. Archived from the original on 7 April 2014. Retrieved 13 February 2022.
"World airline survey". Flight International. 91 (3031): 549, at 595. 13 April 1967. Archived from the original on 28 June 2017. Retrieved 21 February 2022.
Stroud, Michael (21 March 1974). "World airline directory". Flight International. 105 (3393): 1, at 58. Archived from the original on 7 April 2014. Retrieved 13 February 2022.