APA

Watkins H., . (1954). Time counts; the story of the calendar. New York: Philosophical Library.

Chicago

Watkins Harold, . 1954. Time counts; the story of the calendar. New York: Philosophical Library.

Harvard

Watkins H., . (1954). Time counts; the story of the calendar. New York: Philosophical Library.

MLA

Watkins Harold, . Time counts; the story of the calendar. New York: Philosophical Library. 1954.