APA

Willis J. C., . (1973). A dictionary of the flowering plants and ferns. London: Cambridge at the University Press.

Chicago

Willis J C, . 1973. A dictionary of the flowering plants and ferns. London: Cambridge at the University Press.

Harvard

Willis J. C., . (1973). A dictionary of the flowering plants and ferns. London: Cambridge at the University Press.

MLA

Willis J C, . A dictionary of the flowering plants and ferns. London: Cambridge at the University Press. 1973.