APA

Pullan J. M., . (19691968). The history of the abacus. New York: F.A. Praeger.

Chicago

Pullan J M, . 19691968. The history of the abacus. New York: F.A. Praeger.

Harvard

Pullan J. M., . (19691968). The history of the abacus. New York: F.A. Praeger.

MLA

Pullan J M, . The history of the abacus. New York: F.A. Praeger. 19691968.