Unabashedly Onward to the Ninth Planet. [dostęp 2007-05-26]. [zarchiwizowane z tego adresu (2013-12-07)]. Cytat: So on this Web site and in documents, discussions and other aspects of the New Horizons mission, we will continue to refer to Pluto as the ninth planet (ang.).
Unabashedly Onward to the Ninth Planet. [dostęp 2007-05-26]. [zarchiwizowane z tego adresu (2013-12-07)]. Cytat: So on this Web site and in documents, discussions and other aspects of the New Horizons mission, we will continue to refer to Pluto as the ninth planet (ang.).