APA (7th ed.) Citation

Regents pub. co. (1977). The Blue book of business English. Regent Pub.

Chicago Style (17th ed.) Citation

Regents pub. co. The Blue Book of Business English. New york: Regent Pub, 1977.

MLA (9th ed.) Citation

Regents pub. co. The Blue Book of Business English. Regent Pub, 1977.