Kollerstrom, N. «A Neptune Discovery Chronology». The British Case for Co-prediction. University College London, 2001. Arxivat de l'original el 2005-11-19. [Consulta: 23 agost 2007].
web.archive.org
Kollerstrom, N. «A Neptune Discovery Chronology». The British Case for Co-prediction. University College London, 2001. Arxivat de l'original el 2005-11-19. [Consulta: 23 agost 2007].