హేలీ తోకచుక్క: కూర్పుల మధ్య తేడాలు

*{{Cite book|title=Halley & His Comet|url=https://archive.org/details/halleyhiscomet00pete|author=P. Lancaster-Brown|publisher=Blandford Press|year=1985|isbn=0-7137-1447-6}}

*{{Cite book|author=C. Sagan and A. Druyan |title=Comet|url=https://archive.org/details/comet00saga |publisher=[[Random House]]|year=1985|isbn=0-394-54908-2}}