APA

Ridpath I., Murtagh T., . (1985). A comet called Halley. Cambridge [Cambridgeshire]: Cambridge University Press.

Chicago

Ridpath Ian, Murtagh Terence, . 1985. A comet called Halley. Cambridge [Cambridgeshire]: Cambridge University Press.

Harvard

Ridpath I., Murtagh T., . (1985). A comet called Halley. Cambridge [Cambridgeshire]: Cambridge University Press.

MLA

Ridpath Ian, Murtagh Terence, . A comet called Halley. Cambridge [Cambridgeshire]: Cambridge University Press. 1985.