APA

Flexner D., . (1995). The optimist's guide to history. New York: Avon Books.

Chicago

Flexner Doris, . 1995. The optimist's guide to history. New York: Avon Books.

Harvard

Flexner D., . (1995). The optimist's guide to history. New York: Avon Books.

MLA

Flexner Doris, . The optimist's guide to history. New York: Avon Books. 1995.