APA (7th ed.) Citation

Packer, J. C., & Brailsford, D. F. (1973). The OPIT system part I. North-Holland.

Chicago Style (17th ed.) Citation

Packer, John C., and David F. Brailsford. The OPIT System Part I. North-Holland, 1973.

MLA (9th ed.) Citation

Packer, John C., and David F. Brailsford. The OPIT System Part I. North-Holland, 1973.

Warning: These citations may not always be 100% accurate.