Opera Now magazine, accessed 22 October 2010 Marc Okrand speciale gast bij Klingon Opera! (archive), The Flying Dutch, Dutch Star Trek fanclub (in Dutch) Tyler, John.
Opera Now magazine, accessed 22 Οκτωβρίου 2010 Marc Okrand speciale gast bij Klingon Opera! (archive), The Flying Dutch, Dutch Star Trek fanclub (Ολλανδικά) Tyler, John.