APA

O<'= >Brien D., . (1969). Empedocles' cosmic cycle. Cambridge: University Press.

Chicago

O<'= >Brien D, . 1969. Empedocles' cosmic cycle. Cambridge: University Press.

Harvard

O<'= >Brien D., . (1969). Empedocles' cosmic cycle. Cambridge: University Press.

MLA

O<'= >Brien D, . Empedocles' cosmic cycle. Cambridge: University Press. 1969.